LW30-72.5(126)T/T3150-40

Dead-tank SF6 circuit breaker

Outdoor dead-tank SF6 circuit breaker with built-in current transformers and spring-operated mechanism for 72.5 (126) kV, 50 Hz networks. Suited to new and refurbished substations, including seismic regions and cold climates.

Key parameters

Rated voltage: 72.5 / 126 kV
Rated current: 3150 A
Rated short-circuit breaking current: 40 kA
Built-in CT primary current: 300 … 2000 A
Mechanical endurance: 10,000 cycles

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General information

With the development of the power industry, and given that many regions are seismically active or have a cold climate, power systems place ever higher demands on the seismic and low-temperature performance of switchgear; in addition, switching devices are increasingly required to have built-in current transformers. Owing to their design, porcelain-insulated live-tank circuit breakers cannot provide these characteristics either at new substations or in the refurbishment of existing ones. A device is therefore needed that offers high seismic resistance and low-temperature performance, is reliable and economical, and has its own built-in current transformers.

The LW30-72.5(126)T/T3150-40 dead-tank SF6 circuit breaker is a new type of outdoor high-voltage switching device that meets these requirements. It was developed on the basis of many years of experience in high-voltage switching technology and the proven solutions of combined switching devices. It has broad application prospects and is a good choice for new substations and the refurbishment of existing ones.

The LW30-72.5(126)T circuit breaker combines a circuit breaker and current transformers in a single device; the interrupter is mounted horizontally in an earthed aluminium-alloy tank. It is equipped with a CT26 spring operating mechanism. A small number of parts, a simple and compact layout, and a robust, durable design meet the requirements for "oil-free" switchgear; excellent mechanical characteristics and high reliability. All critical parts are machined on CNC machines and machining centres; rolling bearings are used. Mechanical endurance — up to 10,000 operations.

Intended for outdoor three-phase AC 50 Hz high-voltage switchgear — for control and protection in 72.5 (126) kV power transmission and distribution networks; can also be used as a bus-section circuit breaker and for switching capacitor banks.

The product complies with the international standard IEC 62271-100:2001 "High-voltage switchgear and controlgear – Part 100: High-voltage alternating-current circuit breakers". Design, manufacture, inspection, sales and service fully comply with the ISO 9001 quality system, which guarantees the quality of the circuit breaker as a whole.

Service conditions

Ambient air temperature: LW30-72.5T — −40 °C … +40 °C (−50 … +40 °C on special order); LW30-126T — −32 °C … +40 °C (−50 … +40 °C on special order).
Altitude: ≤ 1000 m (not limited for special orders; bushings are adjusted according to altitude).
Air humidity: relative humidity, daily average ≤ 95 %, monthly average ≤ 90 % (25 °C); saturated vapour pressure, daily average ≤ 2.2×10⁻³ MPa, monthly average ≤ 1.8×10⁻³ MPa.
Wind speed: ≤ 35 m/s.
Ice coating thickness: 20 mm.
Seismic intensity: not more than 8 degrees.

Main technical parameters of the circuit breaker

Parameter			Unit	Value
Rated voltage			kV	72.5	126
Rated current			A	3150
Rated short-circuit breaking current			kA	40
Rated short-circuit making current (peak)			kA	100
Rated short-time withstand current			kA	40
Rated peak withstand current			kA	100
Rated duration of short circuit			s	4
First-pole-to-clear factor				1.5
Number of breaks at full rated short-circuit current (cumulative)				20
Rated out-of-phase breaking current			times	10
Short-line fault breaking current			kA	30, 36
Rated line-charging breaking/making current			kA	31.5
Rated operating sequence			A	O – 0.3 s – CO – 180 s – CO
Rated insulation level	Lightning impulse withstand voltage (full wave, peak)	Phase-to-phase and to earth	kV	350	550
	Lightning impulse withstand voltage (full wave, peak)	Across the open gap	kV	410	550+100
	Power-frequency withstand voltage, 1 min	Phase-to-phase and to earth	kV	160	230
	Power-frequency withstand voltage, 1 min	Phase-to-phase and to earth	kV	200	230+70
Rated operating times (at rated voltage)			ms	Opening time: 33 ± 6
Rated operating times (at rated voltage)			ms	Closing time: 85 ± 15
Total break time			cycles	≤ 3
Main circuit resistance per phase			µΩ	≤ 280	≤ 280
Radio interference level			µV	≤ 500
Rated pressure			MPa	0.38	0.38
SF6 alarm pressure (20 °C)			MPa	0.34	0.34
SF6 lockout pressure (20 °C)			MPa	0.30	0.30
Rated voltage of control circuits			V	DC 220 / DC 110
Annual SF6 leakage rate			/ year	≤ 0.3 %
SF6 moisture content (20 °C)			µL/L	≤ 150 (at commissioning)
SF6 moisture content (20 °C)			µL/L	≤ 300 (in service)
SF6 mass			kg	32	40
Mechanical endurance			operations	10000
CT26 mechanism closing/opening coils	Voltage		V	DC 220	DC 110
	Closing coil: current / resistance		A/Ω	2.5/88±3 (20 °C)	4.4/25±1 (20 °C)
	Opening coil: current / resistance		A/Ω	2.5/88±3 (20 °C)	4.8/23±1 (20 °C)
CT26 mechanism motor	Voltage		V	DC 220	AC 220
CT26 mechanism motor	Power		W	600
Dynamic load	Horizontal		N	20000
	Vertical, upward			5000
	Vertical, downward			5000

Circuit breaker assembly and adjustment parameters

Parameter	Unit	Technical requirements	Measurement conditions or method
Pole closing non-simultaneity	ms	≤ 5
Pole opening non-simultaneity	ms	≤ 3
Clearance between output lever roller and cam	mm	1.2 ~ 2.8	All measurements with opening and closing springs charged
Opening electromagnet armature travel	mm	3.4 ~ 5.0
Clearance between opening electromagnet plunger and opening latch	mm	0.7 ~ 1.2	Measured with the mechanism in the "closed" position
Closing electromagnet armature travel	mm	4 ~ 6
Clearance between latch and closing latch	mm	1.0 ~ 2.0	Measured with the mechanism in the "open" position
Clearance between latch and anti-pumping pin	mm	1.0 ~ 2.5

Built-in current transformer parameters

Rated primary current, A	Rated secondary current, A	Rated output, VA	Measuring winding accuracy class*	Measuring winding instrument security factor	Protection winding accuracy class
300	5	30	0.5(0.2)	≤ 5	10P15
400		30	0.5(0.2)		10P15
600		30	0.5(0.2)		10P20
800		40	0.5(0.2)		10P20
1000		50	0.5(0.2)		10P20
1250		50	0.5(0.2)		10P20
1600		50	0.5(0.2)		10P20
2000		50	0.5(0.2)		10P20

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