Overview
The GN30-12 is an indoor rotating-contact-knife high voltage AC disconnector for three-phase 50 Hz systems rated 12 kV (10 kV class). Its three poles share a common base frame carrying two sets of insulators and contacts on upper and lower planes; the knife rotates to open or close the circuit. The GN30-12D adds an earthing switch to suit different system requirements.
Compact, high insulating strength and easy to install and adjust, the design meets GB 1985 (AC high voltage disconnectors and earthing switches). It connects, interrupts or transfers circuits under voltage but without load through a clear visible break, and can be used with a metal-enclosed switchgear cubicle or as a standalone isolator in 400 to 1250 A circuits.
Model Designation
The type is designated G N 30 -12 (D) / □ – □ and decoded as follows:
- G — disconnector
- N — place of use: indoor
- 30 — design sequence number
- 12 — rated voltage in kV
- (D) — with earthing switch
- □ — rated current in A
- □ — thermal-stable current (4 s) in kA
Construction and Operation
- Rotating knife. Each pole has two insulator-and-contact sets on the upper and lower planes of a common frame; the moving knife rotates between them to make or break the circuit with a clear visible gap.
- Compact layout. The three-phase shared-frame design saves panel space while keeping generous insulation distances.
- Earthing option. The D version integrates an earthing switch so the de-energised side can be earthed for maintenance.
- Manual operation. Driven by a manual operating mechanism, interlocked with the associated circuit breaker; it cannot break load or short-circuit current.
Technical Parameters
Rated Parameters
| Item | Unit | GN30-12/400 | GN30-12/630 | GN30-12/1000 | GN30-12/1250 |
|---|---|---|---|---|---|
| Rated voltage | kV | 12 | 12 | 12 | 12 |
| Rated frequency | Hz | 50 | 50 | 50 | 50 |
| Rated current | A | 400 | 630 | 1000 | 1250 |
| Thermal-stable current (4 s) | kA | 12.5 | 20 | 31.5 | 31.5 |
| Dynamic-stable (peak) current | kA | 31.5 | 50 | 80 | 80 |
The GN30-12D (with earthing switch) shares the same electrical ratings as the corresponding GN30-12 current grade.
Rated Insulation Level
| Item | Unit | Phase-to-phase / phase-to-earth | Across the break |
|---|---|---|---|
| 1 min power-frequency withstand voltage | kV | 42 | 48 |
| Lightning impulse withstand voltage (peak) | kV | 75 | 85 |
Normal Service Conditions
- Altitude: not above 1000 m
- Ambient temperature: upper limit +40℃, lower limit −10℃
- Relative humidity: daily average not above 95%, monthly average not above 90%
- Seismic: intensity not above 8 degrees
- Site: free from severe dust, chemical corrosion and explosive substances, and from frequent severe vibration
Installation & Wiring
Installation and Mounting
Fix the shared three-phase base frame to the cubicle mounting plane through the 4 × 25 × 13 (R6.5) mounting holes at the specified phase spacing, keeping the installation plane clear. Couple the poles to the manual operating mechanism (and, on the D version, the earthing switch), then verify free travel of the rotating knives, correct contact seating and the full visible break before energising, and bond the frame to the earth network.
Outline & Mounting Dimensions
| Type | Rated current | A | B | C |
|---|---|---|---|---|
| GN30-12 | 400 / 630 A | ≈ 560 | — | ≈ 315 |
| GN30-12 | 1000 A | ≈ 580 | — | ≈ 332 |
| GN30-12 | 1250 A | ≈ 580 | — | ≈ 295 |
| GN30-12D | 400 / 630 A | ≈ 550 | ≈ 610 | ≈ 240 |
| GN30-12D | 1000 A | ≈ 575 | ≈ 615 | ≈ 245 |
| GN30-12D | 1250 A | ≈ 580 | ≈ 600 | ≈ 295 |
All dimensions in mm and correspond to the outline drawing; mounting holes 4 × 25 × 13 (R6.5).
Selection & FAQs
Selection Guide
- Choose the rated current (400 / 630 / 1000 / 1250 A); thermal- and dynamic-stable currents rise with the current grade.
- Select GN30-12 or the GN30-12D version with earthing switch according to the maintenance-earthing requirement.
- Confirm the mechanism position and interlock against the associated circuit breaker.
Frequently Asked Questions
Q1: What does the type designation GN30-12D mean?
G is the disconnector, N the indoor place of use and 30 the design sequence number; 12 is the rated voltage in kV and D denotes the version with an earthing switch. The trailing figures give the rated current in A and the 4 s thermal-stable current in kA.
Q2: What makes the GN30-12 a rotating type?
Each pole has two insulator-and-contact sets on the upper and lower planes of a shared frame; the moving knife rotates between them to open or close the circuit with a visible break.
Q3: What current ratings are covered?
Four grades — 400 A (12.5 kA / 31.5 kA), 630 A (20 kA / 50 kA), 1000 A (31.5 kA / 80 kA) and 1250 A (31.5 kA / 80 kA), given as 4 s thermal-stable and dynamic-stable (peak) currents.
Q4: Can the GN30-12 break load or short-circuit current?
No. It connects, interrupts or transfers circuits under voltage but without load and provides a visible isolating gap; load and fault currents are handled by the associated circuit breaker.
Q5: What is the insulation level?
1 min power-frequency withstand 42 kV phase-to-phase/earth and 48 kV across the break; lightning impulse withstand 75 kV and 85 kV across the break (peak).
Q6: Where is it used and to what standard?
For 12 kV (10 kV class) three-phase 50 Hz indoor systems, used with a metal-enclosed switchgear cubicle or as a standalone isolator; the design meets GB 1985 for AC high voltage disconnectors and earthing switches. See the disconnector range for related models.