GN30-12M Indoor Rotating HV Disconnector, Panel Type Thomas Electric

Product Overview

The GN30-12M is a panel-type indoor disconnector whose moving knife rotates between two insulator-and-contact sets on a shared three-phase frame, giving a visible isolating gap in 12 kV, 50 Hz metal-enclosed switchgear. Rated for networks of 10 kV and below, it connects, transfers or interrupts circuits that are live but unloaded, in four current grades from 400 A to 1250 A. The M suffix means the assembly sits behind the cubicle panel with the operating shaft brought through it, and adding the D earthing switch yields the GN30-12DM for maintenance earthing of the isolated side.

Product Display

GN30-12M Series Indoor Rotating High-Voltage Disconnector, Panel Type - display

GN30-12M Series Indoor Rotating High-Voltage Disconnector, Panel Type - poster_display

Model Designation

GN30-12M Series Indoor Rotating High-Voltage Disconnector, Panel Type - model

Model format: G N 30 – 12 D M / □ – □

G – disconnector
N – place of use: indoor
30 – design sequence number
12 – rated voltage, kV
D – with earthing switch
M – panel type, mounted behind the cubicle panel
□ – rated current, A
□ – thermal-stable current (4 s), kA
Example: GN30-12DM/630-20 is the panel type with earthing switch at 630 A and 20 kA for 4 s

Service Conditions

Altitude: not exceeding 1000 m
Ambient air temperature: upper limit +40 °C, lower limit -10 °C
Relative humidity: daily average not more than 95%, monthly average not more than 90%
Seismic intensity: not above intensity 8
Installation site free from severe dust, chemical corrosion and explosive substances, and free from frequent severe vibration

Construction

Each pole carries the rotating knife between two ribbed-porcelain insulator-and-contact sets fixed on the upper and the lower plane of one common three-phase base frame. The three poles are coupled to a single operating shaft driven by a manual mechanism at the panel, so the live parts stay behind the cubicle panel while the handle remains accessible from the front.

On GN30-12DM types the earthing knife is interlocked with the main knife and runs on its own shaft, so the isolated circuit can be earthed safely for maintenance. As a disconnector the unit has no load or short-circuit breaking capability and is operated only after the associated circuit breaker has opened the circuit.

Technical Data

Item	Unit	400	630	1000	1250
Rated voltage	kV	12	12	12	12
Rated current	A	400	630	1000	1250
Thermal-stable current	kA	12.5	20	31.5	31.5
Thermal-stable time	s	4	4	4	4
Dynamic-stable current	kA	31.5	50	80	80

Selection note: Start from the rated current of the feeder, then read the thermal-stable and dynamic-stable currents of that column (400 A / 12.5 kA, 630 A / 20 kA, 1000 A / 31.5 kA, 1250 A / 31.5 kA). Choose the panel type M when the switch is mounted behind the cubicle panel and the plain frame type when it is fixed inside the cubicle, and add the D suffix where the isolated circuit has to be earthed for maintenance. Check the 185 x 150 x 50 mm panel against the cubicle; the 170 mm panel-side dimension can be made to order.

Standards

The GN30 series conforms to GB 1985 for AC high-voltage disconnectors and earthing switches. The catalogue parameter table lists each current grade both as GN30-12M and as GN30-12DM, so the same rated data apply to the panel types with and without earthing switch.

Technical note: The catalogue table prints its rated-voltage row as 2; the rated voltage of the series is the 12 kV given by the type designation and the model columns, and the delivered rating is the one on the nameplate. Where a value is fixed by the order, the technical agreement and the nameplate of the delivered switch govern.

Installation & Dimensions

Installation Diagram

GN30-12M Series Indoor Rotating High-Voltage Disconnector, Panel Type - installation

Bolt the three-pole frame to the cubicle mounting surface, fit the panel of the panel type over the frame and pass the operating shaft through it. Couple the poles to the manual mechanism and, on the DM types, the earthing knife to its own shaft. Before energising, check the free travel of the knives, the seating of the contacts and the full visible gap, and bond the frame to the earth network of the cubicle. The certified dimensional drawing issued with the order governs, since the values depend on the ordered rated current and on whether the earthing switch is fitted.

Item	Unit	Value
Overall depth, side view	mm	575
From mounting surface to outer end, panel side	mm	285
From mounting surface, panel side	mm	70
Overall width, front view	mm	760
Phase spacing	mm	250 + 250
Panel, length x width x thickness	mm	185 x 150 x 50
Panel-side dimension, front view (customizable)	mm	170

Safety notice: A disconnector has no load or short-circuit breaking capability: open the associated circuit breaker before operating the knives, keep the interlocks in service, and close the earthing switch only after the circuit has been isolated and proved de-energised. Installation, operation and maintenance must be carried out by qualified personnel, with the frame reliably bonded to the earth network.

FAQs

G marks a disconnector and N the indoor place of use, 30 is the design sequence number and 12 the rated voltage in kV. D adds an earthing switch and M the panel-type mounting, while the fields after the slash give the rated current in A and the 4 s thermal-stable current in kA.

Both use the same rotating knife on a common three-phase frame. In the M panel type the assembly is fitted behind a mounting panel of the cubicle with the operating shaft passing through it, so the handle is accessible from the front and the live parts stay behind the panel; the frame type is fixed inside the cubicle.

Two sets of insulators and contacts are fixed on the upper and the lower plane of the frame, and the moving knife turns between them. Rotation makes or breaks the contact and leaves the visible gap when open, with all three poles coupled to one shaft so they operate together.

No. It connects, transfers or interrupts circuits under voltage but without load. Load and short-circuit currents are interrupted by the associated circuit breaker, which must be open first, and the earthing knife may be closed only after the circuit has been isolated and proved de-energised.

Rated voltage 12 kV at 50 Hz, with rated currents of 400, 630, 1000 or 1250 A. Thermal-stable current is 12.5, 20 or 31.5 kA for 4 s and dynamic-stable current 31.5, 50 or 80 kA; the insulation level is 42 kV power-frequency and 75 kV impulse to phase and earth, 48 kV and 85 kV across the break.

Altitude up to 1000 m, ambient air temperature from -10 °C to +40 °C, relative humidity not above 95% daily and 90% monthly average, seismic intensity not above 8, and a site free from severe dust, corrosion, explosive substances and frequent severe vibration. The panel measures 185 x 150 x 50 mm and the 170 mm panel-side dimension can be made to order.

GN30-12M Series Indoor Rotating High-Voltage Disconnector, Panel Type