FZ(R)N21C-40.5D AC Indoor High-Voltage Vacuum Load Switch

The FZ(R)N21C-40.5D is an indoor high-voltage vacuum load switch designed for 40.5kV wind and photovoltaic power systems. Integrating multiple functions into one compact unit, it features reliable vacuum arc-extinguishing technology. With rated currents from 630A to 1250A and 25kA short-time withstand capacity, this modular switch offers complete protection with optional current-limiting fuses. Its robust construction ensures stable performance in harsh conditions including cold, humid, and polluted environments. Ideal for substations and distribution networks, this load switch provides safe operation with minimal maintenance requirements for renewable energy applications.

product details

Type & Meaning

1	Vacuum load switch
2	R：With fuse base
3	Indoor
4	Design serial number
5	Rated voltage (kV)
6	D：With grounding switch
7	T：Spring operating mechanism
8	Maximum rated current of fuse (A)
9	Rated short-circuit breaking current of fuse (kA)

Normal Service Conditions

a) Ambient temperature: maximum +65°C, minimum -40°C;
b) Ambient humidity:
Daily average relative humidity ≤ 95%, monthly average relative humidity ≤ 90%;
Daily average vapor pressure ≤ 2.2 kPa, monthly average vapor pressure ≤ 1.8 kPa;
c) Altitude: not exceeding 4000 meters;
d) Seismic intensity: not exceeding 8 degrees;
e) Installation site free from fire and explosion hazards;
f) Ambient air not significantly polluted by dust, corrosive or flammable gases, vapors, or salt mist.
Note: Requirements beyond normal service conditions shall be negotiated with the manufacturer.

product Display

Technical Parameters

4.1 The main technical parameters of the load switch are shown in Table 1.

No.	Parameter		Unit	Load Switch	Combination Apparatus
1	Rated Frequency		Hz	50
2	Rated Voltage		kV	40.5
3	Power Frequency Withstand Voltage (1 min)	Phase & Earth / Vacuum Gap		95 Note *
		Isolation Gap		118 Note *
4	Rated Lightning Impulse Withstand Voltage (Peak)	Phase & Earth / Vacuum Gap		185 Note *
		Isolation Gap		215 Note *
5	Auxiliary & Control Circuit Power Frequency Withstand Voltage (1 min)			2
6	Rated Current		A	630,1250	Max. Rated Current of Fuse 63,80,100
7	Rated Short-Circuit Breaking Current		kA	-	31.5,40,50
8	Rated Active Load Breaking Current		A	630,1250	-
9	Rated No-Load Transformer Breaking Current		-	63,125	-
10	Rated Closed-Loop Breaking Current		A	630,1250	-
11	Rated Short-Time Withstand Current (4s)		kA	25	-
12	Rated Peak Withstand Current		kA	63	-
13	Rated Short-Circuit Making Current (Peak)		kA	63	-
14	Rated Transfer Current		A	-	2000
15	Rated Cable Charging Current		A	21
16	Rated Line Charging Current		A	2.1
17	Rated Earth Fault Breaking Current		A	100
18	Mechanical Life (Load Switch / Disconnector / Earthing Switch)		time	10000/2000/2000
19	Rated Operating Voltage		V	≌220/110
20	Permissible Cumulative Wear of Moving & Fixed Contacts		mm	3
21	Contact Gap		mm	18±1
22	Over-Travel			4±1
23	Contact Bounce Time at Closing		ms	≤5
24	Three-Phase Closing/Opening Asynchronism			≤2
25	Average Opening Speed		m/s	1.5±0.3
26	Average Closing Speed			0.8±0.2
27	Main Circuit Resistance (incl. Isolator)		μΩ	≤200	≤300 (excluding fuse)
28	Contact Pressure		N	1600±200
29	Phase-to-Phase Center Distance		mm	440±3 (High-Altitude Type: 500±3)

Note*: Relevant parameters are adjusted according to altitude.

Structure and Principle

Basic Structure

This three-phase load switch/combination unit consists of a frame, solid-insulated poles, a spring operating mechanism, isolation/earthing blades, sensors, and transmission parts. The isolating blades and vacuum interrupters are mounted on the frame. The earthing blades are at the bottom, and the operating mechanism (manual/electrical) is on the left side.

Working Principle

● Vacuum Switch: Uses a spring mechanism for closing and a solenoid/manual knob for opening. AC/DC power is supported. Status is visible through a window.
● Isolation/Earthing Blades: Mechanically interlocked; vacuum switch must be open first. Operated via handle with clear status indication.
● Fuse Trip: Uses striker-type fuses. Any phase fuse operation triggers a mechanical release to open the vacuum interrupter reliably (1–3J trip energy).