Issuance date: September 25^th, 1992                              Execution date: May 1^st, 1993

 

Published jointly by	the National Technical Monitoring Bureau
	the Ministry of Construction of the People’s Republic of China

 

 

中华人民共和国国家标准

National Standard of the People’s Republic of China

 

GB 50060-92

 

Chief Editing Department:              Ministry of Energy Source of the People’s Republic of China

 

Approval Department:         Ministry of Construction of the People’s Republic of China

 

Execution Date:                                 May 1^st, 1993

 

 

 

 

The Notice on the Issuance of the National standard 《Design code for 3 ~ 110kV high voltage electrical installation》

 

JB No. 652 [1992]

 

According to the requirements of the document of JZ No. 2630 [1986] issued by the National Planning Committee, the national standard《Design code for 3 ~ 110kV high voltage electrical installation》set down by Ministry of Energy Source associated with other departments concerned have been jointly checked up by the concerning authorities.  Now 《Design code for 3 ~ 110kV high voltage electrical installation》GB 50060 – 92 is approved to be applied as a mandatory national standard and  shall be executed from May 1^st, 1993.

 

 The original national standard《Design code for  35kV high voltage industrial and civil power distribution installation》GBJ 60-83 shall be abolished simultaneously.

Ministry of Energy Source shall take charge of the management of this code, the affairs of specific explanation, etc., shall be charged by the North-west Electric Power Design Institute under Ministry of Power Energy and the organization of its publishing shall be charged by the Standard Ration Research Institute under the Ministry of Construction.

 

 

                                                           Ministry of Construction of the People’s Republic of China

September 25^th, 1992

 

 

 

Explanations for the revision

 

According to the requirements of the document of JZ [1986] No. 2630 issued by the National Planning Committee, this code was edited by the North-west Electric Power Design Institute under Ministry of Power Energy associated with other departments concerned.

 

During the procedure of emendation, the code emendation group carried out extensive investigation and research work.  The group has seriously summarized the experiences achieved during the execution of the original code, adopted part of the achievements of scientific research, extensively solicited the comments from the departments concerned all over the country and finally examined and finalized the text jointly with the departments concerned.

 

The Code consists of 6 chapters and 3 annexes.  The main content of the amendment includes general principles, common stipulations, environment conditions, conductor and electrical equipment, clear safety distance, selection of type of power distribution installation, passage and enclosure, firefighting and oil storage device, requirement of power distribution installation on buildings and structures.

 

During the execution of this code, If any emendation or supplement are found necessary, the comments and the concerning data are expected to be sent to the Xi An Municipal North-west Electric Power Design Institute (zip code: 710032) for our reference in the future emendation.

 

 

                                Ministry of Energy Source

 

 

 

 

 

 

 

Section 1         Clear safety distance…………………………………………………………11

Section 2         Selection of form ……………………………………………………………17

Section 3         Passage and enclosure………………………………………………………17

Section 4         Firefighting and oil storage device…………………………………………19

 

 

 

 

 

 

 

Article 1.0.1   The establishment of this code is on purpose to make design of high voltage power distribution installation (hereinafter abbreviated as distribution installation) able to realize the technical and economic policy of our country, ensure security and reliability, advanced technology, reasonable economy and easy maintenance.

Article 1.0.2  This code is applicable for design of project of 3 ~ 110kV distribution installations to be newly built or enlarged.

Article 1.0.3  The design of distribution installation shall be according to property and capacity of the power load, environment conditions and requirements of operation, erection and maintenance; selection of equipment and determining of layout scheme shall be made reasonably and effective new technology, new equipment, layout and material shall be applied.

Article 1.0.4   The design of substation shall be in accordance with characteristic, size and development program of the project; the relationship between construction in near future and development at a specified future date shall be handled correctly.  Priority shall be given to construction in near future and possibility of development may be properly taken into consideration.

Article 1.0.5    The principle of economized utilization of land shall be carried out in design of the distribution installation.

Article 1.0.6   In addition to stipulations in this code, other actual stipulations concerning design standard and code of the country shall also be observed.

 

 

Article 2.0.1   The layout of distribution installation and the selection of conductor, electric apparatus and frame structures shall conform to requirement for normal operation, maintenance under local environmental conditions and situations of short circuit and excess voltage.

Article 2.0.2  The arrangement of phase sequence of each circuit of the distribution installation is proper to be consistent and corresponding phase symbol shall be equipped.

Article 2.0.3   For distribution installations of voltage 63KV or 110KV, it is advisable to install grounding knife switch, or other grounding device for each section of bus line and grounding knife is proper to be installed at circuit breaker side of isolating switches at both sides of the circuit breaker and at the circuit side of the circuit isolating switch.

Contact surface or connecting terminals shall be provided on the hard conductor and grounding line within the compartment of indoor distribution installation.

Article 2.0.4   Blocking device shall be established between the isolating switch of indoor or outdoor distribution installation and the corresponding circuit breaker or grounding knife switch. Blocking device shall also be provided for indoor distribution installations preventing entering by mistake.

Article 2.0.5   The arrangement of oil-filling electrical equipment shall meet requirement on safety and convenient observation (with electric charge) of oil level and oil temperature and shall be in convenience of oil sampling.

 

 

Article 3.0.1    Corresponding external insulation standard and other dustproof and corrosion protection measures shall be adopted for electrical equipment and insulators in outdoor distribution installations according to the dirty extent and they shall be in convenience of cleaning.

Article 3.0.2    The selection of environment temperature of naked conductor and electrical equipment shall conform to regulations as listed in Table 3.0.2.

category	installation location	environment temperature (℃)
		highest	lowest
naked conductor	outdoor	the average highest temperature in the hottest month
	indoor	designed ventilation temperature at the location
electrical equipment	outdoor	yearly highest temperature	yearly lowest temperature
	indoor reactors	highest air draft temperature according to designed ventilation temperature for the location
	other locations in the room	designed ventilation temperature for the location

Notes:   ①         The yearly highest (or lowest) temperature means average temperature of multi-years

                        based on the yearly measured highest (or lowest) temperature.

            ②      The average highest temperature in the hottest month means monthly average temperature of multi-years based on the daily measured highest temperature in the hottest month.

            ③      Environment temperature of indoor naked conductor or other electrical equipment shall be selected.  In case no data of designed ventilation temperature for the location is available, the figure of average highest temperature in the hottest month plus 5℃ shall be taken.

Article 3.0.3    For selection of the relative humidity of conductor and electrical equipment, the average relative humidity in the month shown the highest relative humidity shall be adopted.  In humid tropical districts, the type of electrical product suitable to the districts shall be adopted.  Normal electrical equipment may be applied in semi humid tropical districts, but protective measures shall be taken according to local operating experience.

Article 3.0.4    In case ambient temperature is lower than the lowest permissible temperature of electrical equipment, instrument or relay, heating device shall be provided or heat insulation measures shall be taken.

In snow deposit or covering ice seriously affected area, measures preventing emergency caused by snow or ice shall be taken.

Thickness of ice-breaking for isolating switch shall not be less than designed maximum thickness of covering ice.

Article 3.0.5    The average maximum speed of wind at a height 10m above earth happening 10 minutes in every 30 years shall be adopted as the maximum wind speed for distribution installation design and selection of conductor and electrical equipment.  For districts with maximum wind speed exceeding 35m/s, it is advisable that measures such as lowering installation height of electrical equipment, strengthening the fixing of equipment and foundation, etc., shall be taken in the arrangement of outdoor distribution installations.

Article 3.0.6    The antiseismic design of distribution installation shall conform to stipulations as regulated in actual national standard 《Code for antiseismic design of power installation》.

Article 3.0.7    For districts with an altitude exceeding 1000m, the electrical equipment and electric porcelain product suitable to that height shall be applied for distribution installations and the impulsive and power frequency test voltage for their external insulation shall conform to stipulations concerned in actual national standards.

Article 3.0.8    For electrical equipment and anchor clamps of voltage 110kV, no visible glow corona shall be seen at unclouded night under 1.1 times maximum working phase voltage.

The critical voltage of glow corona of 110kV conductor shall be higher than the maximum working voltage where the conductor is installed.

Article 3.0.9    The noise of distribution installations located in residential area and industrial area shall conform to stipulations as regulated in the actual national standard 《Code of noise control design for industrial enterprises》and《Standard of noise in urban area environment》.

 

Article 4.0.1  The maximum permissible working voltage of design selected electrical equipment shall not be lower than the maximum operating voltage of that circuit.

The long term permissible current of design selected conductor and electrical equipment shall be lower than the maximum sustained working current of that circuit; for outdoor conductor and electrical equipment, the influence of sunshine on the current carrying capacity shall also be taken into consideration.

Article 4.0.2  It is not proper to apply copper conductor for bus line and lead wire of distribution installation.

Article 4.0.3    The insulation level of distribution installation shall conform to the stipulations as regulated in the actual national standard《Code for design of excess voltage protection of power installations》.

Article 4.0.4   The short circuit current used for checking calculation of dynamic stability and heat stability of conductor and electrical equipment and switch on(off) current of electrical equipment shall be calculated according to design planned capacity and the long term development layout of electric power system shall also be taken into consideration.

During determination of short circuit current, the calculation shall be according to normal wiring mode of the possible maximum short circuit current.

Article 4.0.5  The short circuit current used for checking calculation of conductor and electrical equipment shall be calculated according to following stipulations:

a.    The resistance of electrical elements may be ignored with exception of decay time constant used for calculating short circuit current.

b.    The influence of asynchronous motor with feedback action and discharging current of capacitor compensation unit shall be considered in electrical connected network.

Article 4.0.6    The dynamic stability and heat stability of conductor and electrical equipment and switch on(off) current of electrical equipment may be checking calculated according to situation of three-phase short circuit.  In case when single-phase or two-phase grounding short circuit is more serious than that of three-phase short circuit, the checking calculation shall be based on the more serious situation.

Article 4.0.7   The main protective action time plus corresponding full switching-off time of circuit breaker is proper to be taken as calculation time of check computation of short circuit thermal effect of the conductor; when main protection contains dead zone, the backup protective action time that takes effect with the dead zone shall be applied and the corresponding short circuit current value shall be adopted.

The backup protective action time plus corresponding full switching-off time of circuit breaker is proper to be applied in checking calculation for electrical equipment.

Article 4.0.8  Checking calculation of dynamic stability and heat stability for voltage transformer circuit under protection of fusible cutout may be exempted.

Checking calculation of dynamic stability and heat stability for conductor and electrical equipment under protection of fusible cutout with high voltage current limitation shall be in accordance with the characteristics of the current limited fusible cutout.

Article 4.0.9    The short circuit current of actual switching on(off) time of the circuit breaker is proper to be taken as the calibration condition for calibrating the current cutout ability of the circuit breaker.

For circuit breakers provided with automatic reclosing unit, the influence of the reclosing on rated switching-on (off) current shall be taken into consideration.

Article 4.0.10    The circuit breaker with superior switching-on (off) property shall be selected as circuit breaker applied in closing capacitor bank with shunt compensation.

Article 4.0.11   The normal maximum working temperature of naked conductor shall not be higher than +70℃ and, considering affect of sunshine, this figure shall not be higher than    +80℃ for aluminum line with steel core and tubal conductor.

When contact surface of naked conductor is reliably covered with tinned (or vitreous enamel) layer, the maximum working temperature may be increased to +85℃.

Article 4.0.12  When short circuit heat stability is checking calculated, the maximum permissible temperature of naked conductor may be +200℃ for hard aluminum and aluminum-manganese alloy and +300℃ for hard copper.  The working temperature with rated load shall be adopted as the temperature of conductor before short circuit.

Article 4.0.13  When section of naked conductor is to be selected according to normal working current of the circuit, the long term permissible current carrying capacity shall be amended according to local altitude and environment temperature.

The long-term permissible current carrying capacity of naked conductor and its coefficient of correction shall be executed according to Annex 1 and Annex 2.

When multi-conductor structure is applied to the conductor, the affect of proximity effect and heat shield on the current carrying capacity shall be taken into consideration.

Article 4.0.14   For 3 ~ 20kV outdoor support insulator and through-wall casing pipe, product with voltage of higher level may be applied and product with voltage of two levels higher may also be applied for 3 ~ 6kV outdoor support insulator and through-wall casing pipe.

Article 4.0.15  During normal operation and in case of short circuit, the maximum acting force of the lead wire of electrical equipment shall not be higher than permissible load of terminal of the electrical equipment.  The mechanical calculation for conductor, casing pipe, insulator and anchor clamp of the outdoor distribution installations shall be proceeded according to local climatic conditions and different stress situations and their safety factor shall not be lower than stipulations as listed in Table 4.0.15.

category	when load is acting in long period	when load is acting in short period
casing pipe, supporting insulator and its anchor clamp	2.5	1.67
suspending insulator and its anchor clamp	5.3	3.3
flexible conductor	4	2.5
hard conductor	2.0	1.67

Notes: ①     The safety factor of suspending insulator is corresponding to the breaking load; in case it is corresponding to 1h electromechanical testing load, the safety factors shall be separately 4 and 2.5.

②     The safety factor of hard conductor is corresponding to the breakdown stress; in case it is corresponding to yielding point stress, the safety factors shall be separately 1.6 and 1.4.

 

Article 4.0.16   During checking calculation of short circuit dynamic stability, the maximum permissible stress of hard conductor shall conform to stipulations as listed in Table 4.0.16.

material of conductor	hard aluminum	hard copper	LF21 type aluminum-manganese alloy
maximum permissible stress (Mpa)	70	110	90

 

The influence of dynamic effect shall also be taken into consideration when stress calculation for hard conductor of important circuits is being made.

Article 4.0.17   Reliable connecting joint shall be provided where conductor is connected to other conductor or electrical equipment.

It is advisable to adopt welding to connections between hard conductors.  Bolts shall be applied where joint needs to be separated and where conductor is connected to terminals of electrical equipment.

When conductors of different metals are to be connected, measures such as transient joint, etc. shall be taken according to ambient conditions.

Article 4.0.18  When hard conductor is applied, expansion joints shall be installed at proper positions or shock proof measures shall be taken according to situations such as temperature variation, uneven deposit or vibration.

 

 

     

 

Article 5.1.1     The clear safety distance of outdoor distribution installation shall conform to stipulations as listed in Table 5.1.1 and shall be calibrated according to Fig. 5.1.1-1, Fig. 5.1.1-2 and Fig. 5.1.1-3.

When the distance between lowest part of the external insulation of electrical equipment and ground surface is shorter than 2.5m, fixed enclosure shall be established.

Article 5.1.2     When flexible conducting wire is applied by outdoor distribution installations, under different conditions, the clear safety distance between electrified part and grounding part and between electrified parts of different phases shall be calibrated according to Table 5.1.2 and the largest value among them shall be applied.

Article 5.1.3     The clear safety distance of indoor distribution installations shall conform to stipulations as listed in Table 5.1.3 and  shall be calibrated according to Fig. 5.1.3-1 and Fig. 5.1.3-2.

When the distance between lowest part of the external insulation of electrical equipment and ground surface is shorter than 2.3m, fixed enclosure shall be established.

Article 5.1.4   When rated voltage of the adjacent electrified parts of the distribution installation are different, the clear safety distance shall be determined according to higher rated voltage.

Article 5.1.5     No illumination, communication or signal line shall pass over or go beneath the electrified part of outdoor distribution installations and no exposed illumination line or power circuit shall pass over the naked electrified part of indoor distribution installations.

Fig. 5.1.1-1  Calibration of outdoor value A₁, A₂, B₁, D

Fig. 5.1.1-2  Calibration of outdoor value A₁, B₁, B₂, C, D

 

Fig. 5.1.1-3  Calibration of outdoor value A₂, B₁, C

symbol	applicable range	rated voltage (kV)
		3~10	15~20	35	63	110J	110
A1	between electrified part and grounding part	200	300	400	650	900	1000
	between the point in the upward extension line of the netlike enclosure, 2.5m above ground, and the electrified part above the enclosure
A2	between electrified parts of different phases	200	300	400	650	1000	1100
	between the electrified parts of lead wire at both sides of the fracture part of circuit breaker and isolating switch
B1	between the side corridor of the equipment being transported and the uncovered electrified part	950	1050	1150	1400	1650	1750
	between the uncovered electrified parts that are intersectant to each other and with different power cut maintenance time
	between barrier shaped enclosure and insulator and between electrified parts
B2	between netlike enclosure and the electrified part	300	400	500	750	1000	1100
C	between naked conductor without enclosure and ground surface	2700	2800	2900	3100	3400	3500
	between naked conductor without enclosure and top of buildings or structures
D	between the uncovered electrified parts that are parallel arranged and with different power cut maintenance time	2200	2300	2400	2600	2900	3000
	between the electrified part and edge of buildings and structures

Notes:   ①         110J indicates power network with its neutral point effectively grounded.

②       Value A shall be amended when the altitude exceeds 1000m.

③       All values listed in this table are not applicable for product design of manufacturers.

condition	calibration condition	calculated wind speed (m/s)	value A	rated voltage (kV)
				35	63	110J	110
lightning overvoltage	lightning overvoltage and wind deviation	10	A1	400	650	900	1000
			A2	400	650	1000	1100
operation overvoltage	operation overvoltage and wind deviation	50% of maximum wind speed designed	A1	400	650	900	1000
			A2	400	650	1000	1100
maximum working voltage	short circuit under maximum working voltage and wind deviation under wind speed 10m/s		A1	150	300	300	450
	wind deviation under maximum working voltage and maximum design wind speed		A2	150	300	500	500

Notes:    Under severe meteorological conditions (e.g. maximum design wind speed not lower than 35m/s) and in areas with biggish wind speed under thunderstorm, the calculated wind speed shall be 15m/s during calibration of clear safety distance under lightning overvoltage.

 

 

symbol	applicable range	rated voltage (kV)
		3	6	10	15	20	35	63	110J	110
A1	between electrified part and grounding part	75	100	125	150	180	300	550	850	950
	between the point in the upward extension line of the netlike and tabular enclosure, 2.3m above ground, and the electrified part above the enclosure
A2	between electrified parts of different phases	75	100	125	150	180	300	550	900	1000
	between the electrified parts of lead wire at both sides of the fracture part of circuit breaker and isolating switch
B1	between barrier shaped enclosure and the electrified part	825	850	875	900	930	1050	1300	1600	1700
	between the uncovered electrified parts that are intersectant to each other and with different power cut maintenance time
B2	between netlike enclosure and the electrified part	175	200	225	250	280	400	650	950	1050
C	between naked conductor without enclosure and ground surface or floor surface	2500	2500	2500	2500	2500	2600	2850	3150	3250
D	between the uncovered naked conductors that are parallel arranged and with different power cut maintenance time	1875	1900	1925	1950	1980	2100	2350	2650	2750
E	between the outlet wire casing pipe leads to open air and surface of outdoor passage	4000	4000	4000	4000	4000	4000	4500	5000	5000

Notes:   ①         110J indicates power network with its neutral point effectively grounded.

②       Value B₂ may be A₁ + 30mm in case tabular enclosure is adopted.

③    The distance between the outlet wire casing pipe leads to open air and surface of outdoor passage shall not be less than value C in the outdoor part as listed in Table 5.1.1.

④       Value A shall be amended when the altitude exceeds 1000m.

⑤       All values listed in this table are not applicable for product design of manufacturers.

Fig. 5.1.3-1  Calibration of indoor value A₁, A₂, B₁, B₂, C, D

Fig. 5.1.3-2  Calibration of indoor value B₁, E

 

 

Article 5.2.1    For selection of distribution installation, local geographical situation and environment conditions shall be taken into consideration.   The form of distribution installation using less land shall be selected preferentially via technical and economical comparison and it should be advisable to observe following regulations:

a.    Indoor distribution unit is proper to be adopted by 35 ~ 110kV distribution installation in urban area or dirty districts;

b.    In center district of big cities or other districts with specially serious environment, SF₆ fully enclosed electrical equipment combination ( abbreviated as GIS) may be applied in 110kV distribution installation.

Article 5.2.2   Indoor arrangement is proper to be applied for GIS.  In case outdoor arrangement is applied for GIS, the influence of ambient conditions such as temperature, daily temperature difference, sunshine, hailstone and corrosion, etc. shall be taken into consideration.

Article 5.2.3    When distribution installation with tubular bus line is applied, the single tube structure of the tubular bus line shall be selected and supporting type is proper to be applied for mode of fixing.

The flexibility of supporting type tubular bus line under condition of no ice and no wind shall not be larger than (0.5 ~ 1.0) D.

Notes: D represents diameter of the tubular bus line.

When tubular bus line is applied, measures shall be taken to separately remove the internal stress against the supporting insulator caused by end effect, breeze vibration and temperature difference.

 

 

Article 5.3.1    The arrangement of distribution installation shall facilitate operation, transportation, maintenance and testing of equipment.

Necessary inspection path and operation terrace shall be provided for outdoor distribution installations.

Article 5.3.2   The minimum width (clear space) of various passages in the distribution installation room shall conform to stipulations as listed in Table 5.3.2.

, sort of passage   mode of arrangement	maintenance passage	operation passage
		fixed type	handcart type
equipment is arranged in one row	800	1500	length of single handcart + 1200
equipment is arranged in two rows	1000	2000	length of dual handcarts + 900

Notes: ①     The width of passage may be decreased for 200mm where individual wall column of the building invades into the passage.

            ②   When handcart type of switch cabinet does not need on-site maintenance, the width of passage may be decreased properly.

③    In case fixed type of switch cabinet is placed against the wall, the distance between  cabinet back and the wall is proper to be 50mm.

④    When 35kV handcart type switch cabinet is applied, it is not proper to make the width of passage behind the cabinet less than 1.0m.

 

Article 5.3.3   A passage shall be provided for indoor arranged GIS.  The width of the passage shall meet the requirement of part transportation, but shall not be less than 1.5m.  For outdoor arranged GIS, the width of the passage shall be determined according to the requirement of field operation.

Article 5.3.4   For indoor arranged oil immersed transformer, the minimum clear distance between its outline and the four sides of wall of the transformer room shall conform to stipulations as listed in Table 5.3.4.

capacity of transformer (kVA)	1000 and below	1250 and above
between transformer and back wall (side wall)	600	800
between transformer and door	800	1000

 

For indoor oil-immersed transformer maintained in situ, the internal height of the transformer room shall be increased by 700mm from the minimum necessary height required by the core lifting and the width may be determined by increasing 800mm at each side of the transformer.  

Article 5.3.5    For dry type transformer installed in the room, the clear distance between its outline and the ambient walls shall not be less than 0.6m.  The distance between dry type transformers shall not be shorter than 1m and it shall also meet the requirement of inspection and maintenance.

The fully enclosed dry type transformer may be exempted from being limited by a.m. regulations.

Article 5.3.6    Enclosure shall be established around the outdoor distribution installation inside  plant area and the height of the enclosure shall not be lower than 1.5m.

Article 5.3.7    The height of the barrier shaped enclosure of the electrical equipment in the distribution installation shall not be lower than 1.2m and the distance between the lowest railing of the barrier shaped enclosure and ground surface shall not be higher than 200mm.

The height of the netlike enclosure of the electrical equipment in the distribution installation shall not be lower than 1.7m and the mesh opening of the netlike enclosure shall not be larger than 40mm × 40mm.

The door of the enclosure shall be provided with a lock.

Article 5.3.8   In the compartment of the room in which oil circuit breaker is installed, in addition to establishment of enclosure, protective separator shall be provided at the operation mechanism of the on-site operated oil circuit breaker and isolating switch.  The width of the separator shall meet the requirement of operating range of personnel and the height of the separator shall not be lower than 1.9m.

Article 5.3.9   When foreign matters are possible to drop onto the bus line laid of outdoor bus line bridge, protective measures shall be taken according to specific situations.

 

 

Article 5.4.1   For indoor distribution installations using 3 ~ 35kV double bus line layout, fire-resisting separator shall be provided between bus line and the isolating switch of the bus line.

Article 5.4.2   When voltage level is 3 ~ 35kV, indoor circuit breaker, oil-immersed current transformer and voltage transformer are advisable to be installed in a compartment equipped with separating wall (plate) at both sides; when voltage level is 63 ~ 110kV, indoor circuit breaker, oil-immersed current transformer and voltage transformer are advisable to be installed in a compartment equipped with explosion proof separating wall.

It is proper to install the indoor oil-immersed power transformer with total oil capacity exceeding 100kg in separated explosion proof compartment provided with firefighting devices. 

Article 5.4.3   When total oil capacity of single set of indoor electrical equipment exceeds 100kg, oil storage or baffling device shall be provided.  The oil baffling device shall be designed according to accommodation of 20% of oil and shall be equipped with facilities to discharge the emergency oil to safety locations.  In case it is impossible to discharge the emergency oil to safety locations, the oil storage device capable of accommodating 100% of oil shall be established.

The selection of inner diameter of the oil discharging pipe shall make it possible to discharge oil as soon as possible and it shall not be less than 100mm.

Article 5.4.4   In locations with higher firefighting requirement, it is advisable to apply non-inflammable or flame resisting transformers when possible.

In the main body of high-rise civil buildings, it is not advisable to apply oil-immersed transformer on ground floor or in basement and the oil-immersed transformers are strictly forbidden to be applied on other floors.

It is also not advisable to apply inflammable circuit breaker in the distribution installations installed in the main body of high-rise civil buildings

Article 5.4.5   When oil capacity of single oil tank of the outdoor oil-filling electrical equipment exceeds 1000kg, an oil reservoir capable of accommodating 100% of oil or an oil reservoir that may contain 20% of oil together with an oil baffling wall shall be established.

When the oil reservoir that may contain 20% of oil together with the oil-baffling wall is applied, facilities to discharge the oil to safety locations shall be provided and this should not lead to pollution hazard.  In case a general emergency oil reservoir with oil water separation device is established, its capacity shall not be smaller than 60% of capacity of the biggest oil tank.

The length and width of the oil reservoir and oil baffling wall may be calculated in a way that 1m shall be added to the length of each corresponding side of the outline of equipment.

The edge of the oil reservoir shall be 100mm higher than ground surface.  It is advisable to pave a layer of pebble stone in the oil reservoir with a thickness not less than 250mm and the diameter of the pebble stone is proper to be 50 ~ 80mm.

Article 5.4.6   When no firewall is provided between outdoor oil-immersed transformers with oil weight larger than 2500kg each, the minimum clear fireproof distance shall conform to stipulations as listed in Table 5.4.6.

level of voltage (kV)	minimum clear fireproof distance (m)
35 and below	5
63	6
110	8

 

Article 5.4.7  When it is necessary to establish firewall between outdoor oil-immersed transformers, the height of the firewall is not proper to be lower than that of the top of conservator of the transformer.  Both ends of the firewall shall be separately longer than each side of transformer oil reservoir for 0.5m.

Article 5.4.8    When the distance between outer wall of buildings with fire hazard category of class C, D or E and outline of the outdoor oil-immersed transformer is less than 5m, there shall be no doors, windows or ventilation holes to be established on the outer wall within the scope of (vertically) below the horizontal line 3 meters above the height of transformer and (horizontally) adding 3 meters to each side of the outline of transformer.  When distance between outer wall of the building and the outline of transformer is less than 10m, fire-retarding door may be established on the outer wall and fixed non-inflammable windows may be established above the height of transformer.

Notes: When oil capacity of 3 ~ 10kV transformer is less than 1000kg, adding 1.5 meters to each side of the outline of transformer shall be sufficient.

 

 

Article 6.0.1    The Structure of distribution installation room shall meet following requirements:

a.    Two exits shall be provided for the distribution installation room with its length over 7m and they shall be arranged at both ends of the distribution installation room; when the length exceeds 60m, another exit shall be added; In case the distribution installation room is a storied building, one exit may be established at the platform leads to outdoor staircases.

b.    It is advisable to establish a separating wall with door opening at the section separation point of bus line of the packaged type distribution installation.

c.    In case the door of the room containing oil-filled electrical equipment opens toward interior of buildings not in the line of power distribution installation, the door shall be a solid door made of non-inflammable or flame resisting material.

d.    Fire-retarding door shall be established for the distribution installation room and the door shall be open outward.  The fire-retarding door shall be provided with a spring lock and door bolt is strictly forbidden to be applied. In case a door is provided between two adjacent distribution installation rooms, the door shall be able to be open in both directions.

e.    Windows may be provided for the distribution installation room but measures shall be taken to prevent snow, rain, small animals, blown sand and dirty dust from entering into the room.  It is not advisable to install windows on the side of the distribution installation room, which is close to the street. 

f.     The fire resistance rating of the distribution installation room shall not be lower than class 2.

The surface of ceiling and inner wall of the distribution installation room shall be treated.  The ground surface and floor surface shall be trowel finished with high-grade cement and terrazzo ground surface may also be applied by the distribution installation room of GIS. 

g.    In case the distribution installation room is a storied building, waterproof measures shall be taken for the building floor.

h.         Emergency air draft devices shall be established for the distribution installation room        according to requirement of emergency fume exhausting.  The distribution installation    room of GIS shall be provided with air draft and ventilation devices.

i.     Unblocked traffic shall be ensured in passages inside the distribution installation room and no doorsills shall be established.  The pipe lines not related to the distribution installation shall not pass through the distribution installation room.

Article 6.0.2    The loading condition of the frame of out door distribution installation shall conform to following requirements:

a.    The climatic conditions used for calculation shall be determined according to local meteorological data.

b.    Design of frame shall be in accordance with terminal and intermediate frame separately on the basis of actual stress conditions.

Wire disconnection shall not be taken into consideration in frame design.

c.    Four kinds of loading combination during situation of operation, installation, maintenance and earthquake shall be considered in frame design:

Situation of operation: Three kinds of situation such as maximum wind (under corresponding temperature and with no ice), the minimum temperature (with no ice and wind) and the most serious ice covering (under corresponding temperature and wind speed) that would occur once in 30 years as well as the corresponding tensile force and self-weight of conducting wire and lightning protecting wire, etc. shall be taken into consideration.

Situation of installation: For erection of guide line and lightning protecting wire, the weight of operator working on the beam together with his (her) tool 2kN as well corresponding wind loading, tensile force and self-weight of conducting wire and lightning protecting wire, etc. shall be taken into consideration.

Situation of maintenance: According to the necessity of actual mode of maintenance, power-cut maintenance with operators working on three phases simultaneously (the weight of operator working at the root of insulator of conducting wire of each phase and tool is 1kN) and single-phase plus neutral point power-on maintenance (weight of operator and tool is 1.5kN) may be considered and the tensile force and self-weight of conducting wire in these two cases as well as corresponding wind loading shall be taken into consideration.  In case no wire is lead down within scope of cable section, manual operation against the neutral point may be exempted from consideration.

Situation of earthquake: The horizontal earthquake action and the corresponding wind loading (or corresponding ice loading) as well as tensile force and self-weight of conducting wire and lightning protecting wire, etc. shall be taken into consideration.  The structural resistance or design strength under earthquake situation is permissible to be increased by 25% and applied.

Article 6.0.3    The design of building and structure of the distribution installation shall also conform to stipulations as regulated in the actual national standard《Code for design of 35 ~ 110kV electric substation》.

 

 

size of conductor h'b mm'mm	single strip		two strips		three strips		four strips
	flat placement	vertical placement	flat placement	vertical placement	flat placement	vertical placement	flat placement	vertical placement
40'4	480	503
40'5	542	562
50'4	586	613
50'5	661	692
63'6.3	910	952	1409	1547	1866	2111
63'8	1038	1085	1623	1777	2113	2379
63'10	1168	1221	1825	1994	2381	2665
80'6.3	1128	1178	1724	1892	2211	2505	2558	3411
80'8	1274	1330	1946	2131	2491	2809	2863	3817
80'10	1427	1490	2175	2373	2774	3114	3167	4222
100'6.3	371	1430	2054	2253	2633	2985	3032	4043
100'8	1542	1609	2298	2516	2933	3311	3359	4479
100'10	1728	1803	2558	2796	3181	3578	3622	4829
125'6.3	1674	1744	2446	2680	2079	3490	3525	4700
125'8	1876	1955	2725	2982	3375	3813	3847	5120
125'10	2089	2177	3005	3282	3725	4194	4225	5633

Notes:

①       Calculation of current-carrying capacity is in accordance with conditions of maximum permissible temperature +70℃, referential ambient temperature +25℃, no wind and no sunshine.

②       In the column “size of conductor” of above table, h indicates width and b indicates thickness. 

③       In above table, when number of conductor is 4 strips , no matter the conductor is flat placed or vertically placed, the distance between the 2^nd and 3^rd strip is 50mm.

 

section size (mm)				section area of double groove conductor  (mm2)	coefficient of surface action Kf	current-carrying capacity of conductor (A)	[   ]	[  ]	[  ]	[   ]	[   ]	[   ]	when double grooves are welded into a whole body				maximum permissible distance of resonance (cm)
h	b	c	r				section coefficient         wy（cm3）	moment of inertia          Iy（cm4）	radius of inertia               ry（cm）	section coefficient         wx（cm3）	moment of inertia          Ix（cm4）	radius of inertia               rx（cm）	section coefficient         wyo（cm3）	moment of inertia          Iyo（cm4）	radius of inertia               ryo（cm）	static moment                     Syo（cm3）	space between insulators when double grooves are connected actually	space between insulators when double grooves are not connected actually
75 75 100 100 125 150 175 200 200 225 250	35 35 45 45 55 65 80 90 90 105 115	4.0 5.5 4.5 6.0 6.5 7.0 8.0 10.0 12.0 12.5 12.5	6 6 8 8 10 10 12 14 16 16 16	1040 1390 1550 2020 2740 3570 4880 6870 8080 9760 10900	1.012 1.025 1.020 1.038 1.050 1.075 1.103 1.175 1.237 1.285 1.313	2200 2620 2740 3590 4620 5650 6600 7550 8800 10150 11200	2.52 3.17 4.51 5.9 9.5 14.7 25 40 46.5 66.5 81	6.2 7.6 14.5 18.5 37 68 144 254 294 490 660	1.09 1.05 1.33 1.37 1.65 1.97 2.40 2.75 2.70 3.20 3.52	10.1 14.1 22.2 27 50 74 122 193 225 307 360	41.6 53.1 111 135 290 560 1070 1930 2250 3450 4500	2.83 2.76 3.78 3.70 4.70 5.65 6.65 7.55 7.60 8.50 9.20	23.7 30.1 48.6 58 100 167 250 422 490 645 824	89 113 243 290 620 1260 2300 4220 4900 7240 10300	2.93 2.85 3.96 3.85 4.80 6.00 6.90 7.90 7.90 8.70 9.82	14.1 18.4 28.0 36 63 98 156 252 290 390 495	178 205 203 228 252 263 285 283 299 321	114 125 123 139 150 147 157 157 163 200

Notes:

①    Calculation of current-carrying capacity under maximum permissible temperature +70℃ is in accordance with conditions of referential ambient temperature +25℃, no wind, no sunshine, without painting and the radiant heat-extraction coefficient and heat-absorption coefficient are all 0.5.

②    Calculation of current-carrying capacity under maximum permissible temperature +80℃ is in accordance with conditions of referential ambient temperature +25℃, sunshine 0.1w/cm², wind speed 0.5m/s, altitude 1000m, without painting and the radiant heat-extraction coefficient and heat-absorption coefficient are all 0.5.    

③    In the column “size of conductor” of above table, D indicates outer diameter and d indicates inner diameter.

 

 

 

 

 

 

 

 

Annex 3   Explanation of Wording in This Code

a.   Words denoting the different degrees of strictness are explained as follows in order that they can be distinguished from each other during the Implementation of this code:

(1)  Words denoting a very strict or a mandatory requirement:

“must” is used for affirmation;

“must not” is used for negation.

(2) Words denoting a strict requirement under normal conditions:

“shall” is used for affirmation;

“shall not” is used for negation.

(3)   Words denoting a permission of slight choice or an indication of the first choice when conditions allow:

“should” or “may” are used for affirmation;

“should not” is used for negation.

b.    “Be in accordance with” or “be in compliance with” are used in the text of this code for those items that name the related standards, codes or regulations as a must requirement to implement this code.