Technical Specification Disconnecting Circuit Breakers

Technical Specification Disconnecting Circuit Breakers

Specification identification: DCB 72,5 – 800 kV

Create date: 2015-10-23

Technical Specification for

Disconnecting Circuit Breakers between 72.5 – 800 kV

Based on

International Electrotechnical Commission (IEC)

TABLE OF CONTENT

1 Disconnecting circuit breakers 3

1.1 Scope 3

1.2 General requirements 3

1.3 Standards 3

1.4 Service conditions 3

1.5 Disconnecting circuit breaker ratings 3

1.6 Design requirements 4

1.6.1 Density monitoring 4

1.6.2 Operating mechanisms disconnecting circuit breaker 4

1.6.3 Locking Mechanism disconnecting circuit breaker 5

1.6.4 Earthing switch (if applicable) 5

1.6.5 Electrical interlocking disconnecting circuit breaker 6

1.6.6 Support structures 6

1.6.7 Central control cabinet/Integrated control cabinet (when applicable) 6

1.6.8 Controlled switching (when applicable) 7

1.7 Tests 8

1.7.1 Type tests on disconnecting circuit breakers 8

1.7.2 Routine tests on disconnecting circuit breakers 8

2 Technical schedule disconnecting circuit breaker 9

3 REVISION HISTORY 20

Table of figures

Table 1 Electrical interlocking scheme of DCB 6

Table 2 Zink coating table 6

Table 3 Ambient and site conditions 9

Table 4 General and common data for all disconnecting circuit breakers 9

Table 5 Specification DCB 72.5kV 10

Table 6 Specification DCB 123kV 11

Table 7 Specification DCB 145kV 12

Table 8 Specfication DCB 170kV 13

Table 9 Specification DCB 245kV 14

Table 10 Specification DCB 300kV 15

Table 11 Specification DCB 362kV 16

Table 12 Specification DCB 420kV 17

Table 13 Specification DCB 550kV 18

Table 14 Specification DCB 800kV (Not Applicable for 60Hz) 19

1  Disconnecting circuit breakers

1.1  Scope

These specifications cover general requirements for the design, manufacture and testing of disconnecting circuit breakers (DCB).

1.2  General requirements

The disconnecting circuit breakers (DCB) shall be of the live tank type for outdoor installation, using SF6 or alternative environmental friendly extinguishing medium gas as the insulating and current extinguishing medium. Oil and vacuum is not accepted.

For disconnecting circuit breakers with single-pole operation, local and remote three-pole operation shall be possible.

The operating mechanism should preferably be of the motor-charged spring type. However, other types of mechanisms can be considered, e.g., motor drives.

The manufacturer shall ensure trip-free operation.

Neither pre-insertion resistors nor grading capacitors bridging the isolating distance will be accepted.

1.3  Standards

All apparatus shall be of latest design and shall fulfill all relevant requirements stated in applicable standards, referred to for each apparatus.

Summary of important Standards for this specification:

IEC 62271-108 High-voltage switchgear and controlgear – Part 108: High-voltage alternating current disconnecting circuit-breakers for rated voltages of 72,5 kV and above

IEC 62271-100 High-voltage switchgear and controlgear – Part 100: Alternating-current circuit-breakers

IEC 62271-102 High-voltage switchgear and controlgear – Part 102: Alternating current disconnectors and earthing switches

Summary of important Guidelines for this specification:

IEC 62271-300 Guideline for High-voltage alternating current circuit-breakers - Guide for seismic qualification of high-voltage alternating current circuit-breakers

1.4  Service conditions

The manufacturer shall ensure that the disconnecting circuit breakers (DCB) will operate satisfactorily in installations with service conditions as specified under Table 3 Ambient and site conditions.

1.5  Disconnecting circuit breaker ratings

The disconnecting circuit breakers (DCB) shall comply with the data indicated under Table 4 General and common data for all disconnecting circuit breakers and relevant DCB specification.

1.6  Design requirements

1.6.1  Density monitoring

The disconnecting circuit breakers (DCB) shall be provided with temperature-compensated density meters for indication of low gas density (using reference volume). The density meters shall monitor gas pressure and provide outputs as follows: should the gas density fall to the recommended density levels for refill/low gas density and trip-close/lockout:

- Stage 1 Alarm
- Stage 2 Trip-close/Lockout

The outputs of the density meters shall include contacts for substation alarm and lockout of all operation of the disconnecting circuit breaker.

Each density meter should include a manometer, readable from ground level, preferably with a scale with indication of the absolute pressure in MPa. One density meter per operating mechanisms is preferable.

The disconnecting circuit breakers shall have a mechanically linked indication system which at all times gives a clear and unambiguous representation of the position of the main contacts – preferable one per pole. The indication shall be easily readable from ground level.

1.6.2  Operating mechanisms disconnecting circuit breaker

The operating mechanism cabinets shall include the following features and equipment:

·  A control panel with three (four) selector switches;

o  Positions LOCAL-REMOTE-DISCONNECTED

o  Control switch ON/OFF for circuit breaker operation)

o  Control switch LOCK/UN-LOCK for locking device operation

o  (OPTIONAL) Control switch OPEN/CLOSE for earthing switch operation

·  The springs shall be charged by an electric motor, preferably a universal type. The motor shall be protected by a miniature circuit breaker with auxiliary contacts for indication. When the springs are charged, a contactor controlled by a limit switch shall disconnect the motor circuit.
A mechanical or electrical indication, visible from outside the cabinet, shall indicate when the springs are fully charged or un-charged.
Under no conditions shall it be possible to perform closing or tripping operations without the appropriate springs being fully charged.

·  The operating mechanism shall include features for charging the closing springs manually by means of a lever. When the lever is used the motor circuit shall be de-energized.

·  Relays for lockout ON/OFF operation of the disconnecting circuit breaker in case the gas pressure has dropped to the lockout level.

·  Heating elements; one element permanently energized and one operated by a thermostat, or alternatively, a humidity detector. The heating elements shall be protected by a miniature circuit breaker with auxiliary contacts.

·  The wiring in the cabinet should be carried out with stranded copper cable with sufficient cross-section area to withstand the currents flowing in auxiliary, control and motor circuits. The cables should be marked along its’ whole length with wiring number and destination.

1.6.3  Locking Mechanism disconnecting circuit breaker

The Locking mechanism for the DCB shall provide the following:

·  When DCB is locked in open position, operation of the circuit breaker should be both mechanically locked and electrically disabled.

·  Motor operation from remote or local. Manual operation as backup.

· Electrical interlocking between the DCB, and if applicable earth switch, for safe operation according to Table 1 Electrical interlocking scheme of DCB.

·  A facility shall be provided to externally padlock the DCB in “locked” position.

·  The padlock holes shall be accessible from the ground level.

·  The indication of DCB being locked in open position shall be visible from ground level, by use of suitable indication, with the control cabinet door closed.

1.6.4  Earthing switch (if applicable)

The Earthing switch for the disconnecting circuit breaker (DCB) shall contain the following features:

·  The earthing switches shall be motor-operated with manual operation as a back-up. The mechanism shall be equipped with a mechanical lever for manual operation during maintenance and emergency operation. When the lever is used, the motor circuit shall be isolated.

·  The operating mechanism should be located in painted aluminum cabinet, same requirements for corrosion resistance and degree of protection as the operating mechanism of the disconnecting circuit breaker.

·  A heating element shall be included in the operating mechanism of the earthing switch.

·  The earthing switch shall be operated by a motor connected to the operating shaft, either directly or through a gear train.

·  The motor shall be operated remotely or at disconnecting circuit breaker control cabinet and should be protected by a miniature circuit breaker.

·  When the earthing switch has reached its end position, the motor circuit shall be interrupted by a limit switch.

·  Selector switch [REMOTE-LOCAL-DISCONNECTED] for earthing switch should be common with the disconnecting circuit breaker selector switch and located the disconnecting circuit breaker operating mechanism or in the central control cabinet.

·  Connection from disconnecting circuit breaker is made by quick connection terminals.

·  Electrical interlocking between the DCB, and locking device, for safe operation according to Table 1 Electrical interlocking scheme of DCB.

·  Pad-lockable in open and closed position

The requirements specified for the control panel, terminals and internal cabling in the disconnecting circuit breaker operating mechanism are also valid for the operating mechanism for the earthing switch.

1.6.5  Electrical interlocking disconnecting circuit breaker

Table 1 Electrical interlocking scheme of DCB

Electrical interlocking in DCB
Main switch position / Electrical interlocking for DCB
Local / Operation only possible from breaker
Remote / Operation only possible from control room
Disconnected / No operation possible
Breaker position / Breaker operation possible / Operation of locking device possible / Operation of Earthing Switch possible (if built on)
Closed / Yes / No / No
Open / Yes / Yes / No
Open and locked / No / Yes / Yes
Open, locked and earthed / No / No / Yes

1.6.6  Support structures

Each disconnecting circuit breaker pole should be mounted on its separate support structure. Alternatively, the three poles can be mounted on a common support beam.

The support structure should be made of hot-dip galvanized steel.

The zinc coating shall comply with EN-ISO 1461, DIN 50976 or ASTMA123 and ASTMA153 (for fasteners).

Table 2 Zink coating table

Steel thickness (mm) / Average zinc coating (mm)
>6 / 115
3-6 / 95
1-3 / 70

The support structure should be of a sufficient height, providing minimum 2.25 meters ground clearance to lower part of insulator.

1.6.7  Central control cabinet/Integrated control cabinet (when applicable)

Applicable for single pole operated disconnecting circuit breakers. In order to achieve local three-pole operation of single-pole operated disconnecting circuit breakers, a central control cabinet (CCC)/integrated control cabinet (ICC) should be provided.

The central cabinet should include selector switches for operation and position selection as described under Operating mechanisms disconnecting circuit breaker above.
The requirements for internal cabling and terminals in the operating mechanism cabinets are otherwise valid.

1.6.8  Controlled switching (when applicable)

Controlled switching by means of adaptive type will be the preferred method, unless it can be proven by field experience that said method does not dramatically improve system reliability/operability.

For energizing of no-load transformers, controlled switching by means of remnant flux calculation is preferable; however this shall be observed on a case-by-case basis, depending on field experience with similar system configuration characteristics.

1.7  Tests

1.7.1  Type tests on disconnecting circuit breakers

The following mandatory type tests should be carried out in accordance with IEC 62271-108:

·  Dielectric tests

·  Radio interference tests

·  Measurement of the resistance of the main circuit

·  Temperature rise tests

·  Short-time withstand current and peak withstand current tests

·  Verification of the degree of protection

·  Tightness tests

·  Mechanical (M1/M2 class) and environmental tests

·  Basic short-circuit test duties

·  Short-line fault tests

·  Out-of-phase making and breaking tests

·  Capacitive current switching tests

·  Tests to verify the proper function of the position indicating device

·  Electrical Endurance Combined Function Test

·  Mechanical Endurance Combined Function Test

In addition to the mandatory type tests as per IEC 62271-108, the following tests should be carried out when applicable:

§  Switching of shunt reactors in accordance with IEC 62271-110

§  If required by geographic location, seismic withstand verifications are recommended as per guideline IEC 62271-300. Calculations of the circuit breakers withstand capability against seismic action are also acceptable.

Type tests shall be performed by an independent accredited European laboratory. If the manufacturer can show evidence through certified reports on performed type tests on the disconnecting circuit breakers, the requirements for execution of tests can be waived.

1.7.2  Routine tests on disconnecting circuit breakers

The disconnecting circuit breakers shall be routine tested in accordance with IEC62271-108.

Eventual Earthing switch may be tested separately as long as interlocking in secured according to circuit diagram.

2  Technical schedule disconnecting circuit breaker

Table 3 Ambient and site conditions

DISCONNECTING CIRCUIT BREAKER SPECIFICATION
Parameter description for
disconnecting circuit breaker / UNIT/options / Schedule A / Schedule B
Min. Required Data / Guarantee data
AMBIENT AND SITE CONDITIONS
Temperature range :
- Minimum temperature / [°C] / -25
- Maximum temperature / [°C] / +40
Site altitude
If site altitude is higher than 1000 m.a.s.l. supplier must do the altitude correction and provide suitable equipment. / m.a.s.l. / ≤1000
Seismic qualification level / AF1/AF3/AF5
Minimum nominal specific creepage distance / [mm/kV] / 25
Wind velocity / [m/s] / 34
Ice class / [mm] / 10

Table 4 General and common data for all disconnecting circuit breakers

GENERAL/COMMON DATA FOR ALL DISCONNECINTG CIRCUIT BREAKERS
Standards to fulfill/test against / - / IEC 62271-108
IEC 62271-100
Frequency / [Hz] 50/60 / 50
Operating voltage / [V DC] / XXX (+10% -15%)
Motor / [V DC] / XXX (+10% -15%)
Heater / [V AC] / XXX
Number of trip coils / - / 2
Number of close coils / - / 1
Manual trip / - / Yes, Internal
Electro-Mechanical trip counter (non-resettable) / - / Yes
Anti pumping relay / - / Yes
Spring Charge Indication / - / Yes
Trip Coil Supervision / - / Yes, Internal
Miniature circuit breaker (MCB) / - / Yes, heater and motor circuit
Under voltage relay / - / No
Minimum number of free auxiliary contacts (NO/NC) in DCB operating mechanism / 5/5
Minimum number of free auxiliary contacts (NO/NC) in earthing switch operating mechanism / 2/2
Bursting disc / - / No
HV Terminals / IEC(40) 9−hole +
NEMA(44.5) 4−hole
Light in cabinet(s) / - / Yes, LED
Creepage distance (phase to phase) / [mm/kV] / 25
Type of insulator and color / - / Composite/Grey with silicone rubber
Type of cubical / - / Painted Aluminum
Protection class / - / IP55
Corrosion class / - / C4

Table 5 Specification DCB 72.5kV

Specific data for DCB 72.5kV
All circuit breakers should be tested in accordance with IEC 62271-100 & IEC 62271-108 / Requested ratings / Offered ratings
Type designation / - / Show product name
Type of operation / 1-pole/3-pole / 3-pole
Number of poles / - / 3
Phase to phase distance / [mm] / 1500
Type of drive / Spring/Motor / Spring
DIELECTRIC CHARACTERISTICS
Rated Voltage / [kV] / 72.5
Lightning impulse withstand voltage :
- phase-to-earth / [kV] / 325
- across the open switching device / [kV] / 375
Switching impulse withstand voltage :
- phase-to-earth / [kV] / N/A
- across the open switching device / [kV] / N/A
Power frequency withstand voltage :
- phase-to-earth / [kV] / 140
- across the open switching device / [kV] / 160
Continuous current / [A] / 2750
Rated short-circuit breaking current: / [kA] / 31.5
Duration / [s] / 3
DC time constant / [ms] / 45
First-pole-to-clear factor / 1.3/1.5 / 1.5
Capacitive current switching class / C1/C2 / C2
Line charging breaking current / [A] / 10
Cable charging breaking current / [A] / 125
Single/Back to Back capacitor bank switching current / [A] / -
OTHER INFORMATION
Filling pressure at 20°C / [MPa(abs)] / State your value
Insulating gas type / - / SF6(SF6/N2; SF6/CF4)
or CO2 + O2
CT brackets included on support structure / Yes/No / Yes
MECHANICAL CHARACTERISTICS
Opening time / [ms] / (XX±X)
Closing time / [ms] / ≤60
Breaking time / [ms] / 50
Mechanical endurance class / M1/M2 / M2
Rated operating sequence / - / O-0.3s-CO-3min(s)-CO
EARTHING SWITCH DATA (referring to IEC 62271-102)
Earthing switch built on to DCB / Yes/No / Yes
Type of operation, Rated short circuit current, Rated voltage level, Rated frequency, Rated insulation level / - / Same as DCB
Mechanical endurance class / - / M1
General class / - / Class A
Electrical endurance class / - / E0
Operation / - / Local/Remote/Manual
Padlocking possible in positions Open and Close / - / Yes

Table 6 Specification DCB 123kV