GGD1 / GGD2 / GGD3 Series AC Low Voltage Main Incoming Distribution Cabinet

1. Product Overview

GGD series fixed-type low-voltage switchgear is designed for AC 50/60Hz, rated working voltage 400V three-phase four-wire power distribution systems. As the main incoming cabinet of low-voltage distribution rooms, it undertakes power receiving, overall system protection, electrical metering, voltage & current monitoring, and centralized power transmission to bus sections.

This cabinet strictly complies with IEC 60439-1 and GB 7251.1 standards, adopting 8MF cold-bent steel frame with strong structural rigidity and IP30 protection grade. It is widely matched with 10kV KYN28A-12 medium voltage switchgear, dry-type transformers, bus coupler cabinets, capacitor compensation cabinets and feeder cabinets, serving industrial plants, commercial complexes, substations, data centers, photovoltaic power stations and various overseas power engineering projects.

GGD1, GGD2 and GGD3 differ mainly in short-circuit withstand capacity, rated current and applicable load scale, covering small, medium and large power distribution scenarios respectively.

2. Main Internal Configuration of Main Incoming Cabinet

1. Main Air Circuit Breaker (ACB) Core switching device for total power control, equipped with overload, short-circuit, undervoltage protection, electric manual closing & tripping function.
2. Isolation Disconnector Provides visible breaking point for safe maintenance of rear busbar and equipment.
3. Current Transformer (CT) Matches multi-function power meter, ammeter and power factor meter for metering and signal sampling.
4. Measuring Instrument Panel Installed with voltmeter, ammeter, power factor meter, transfer switch, closing/tripping buttons and running/fault indicator lights.
5. Surge Protection Device (SPD) Absorbs lightning and switching overvoltage to protect all low-voltage equipment insulation.
6. Main Copper Busbar System Top-mounted L1/L2/L3 phase busbars, independent N neutral busbar and PE grounding busbar; all bus joints are tinned to reduce contact resistance.
7. Complete Secondary Terminal Block Concentrated wiring for protection, measurement, signal and remote communication circuits.

3. Technical Parameter Comparison of GGD1 / GGD2 / GGD3

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4. Working Principle

The low-voltage 400V power output from the secondary side of the dry-type transformer is connected to the top copper busbar of the GGD main incoming cabinet via bus duct. The power passes through the isolating switch and main ACB in sequence, then transmitted to the main busbar running through the whole row of low-voltage cabinets.

• Normal operation: The main incoming breaker remains closed, distributing power to bus coupler cabinet, compensation cabinet and multiple feeder cabinets simultaneously.
• Fault state: Once short-circuit, overload or undervoltage occurs, the main breaker trips automatically to cut off power supply of the whole bus section to avoid equipment damage and safety accidents.
• Measurement & monitoring: CT collects current signals to real-time display voltage, current and power data on the instrument panel, and supports remote data uploading via communication modules.

5. Core Product Advantages (For Foreign Trade Website)

1. Three specifications for full coverage GGD1 for light load, GGD2 universal standard type, GGD3 high-current heavy-duty type, flexible to match all kinds of power distribution schemes.
2. Safe and reliable fixed structure Integrated steel frame, fully isolated busbar compartment, prevent accidental touch of live parts, meet international power grid safety standards.
3. Complete multi-layer protection system Main circuit breaker protection + SPD surge protection + overall cabinet grounding protection, effectively resist short-circuit and overvoltage risks.
4. Convenient installation and maintenance Front operation design, clear zoning layout of primary and secondary circuits, cable inlet at the bottom, easy wiring and later inspection.
5. Strong system compatibility Can be combined with bus coupler cabinet, reactive power compensation cabinet and feeder cabinet arbitrarily to form single-section or double-section bus power distribution system.
6. Customizable for global markets Supports 50Hz / 60Hz frequency switching, different rated current configurations, and English instrument panel & nameplate for overseas projects.
7. High cost performance Compared with withdrawable MNS/GCS cabinet, GGD fixed type has lower purchase and maintenance cost, widely recognized by global industrial customers.

6. Application Scenarios

• GGD1 Main Incoming Cabinet: Small factories, residential communities, small commercial buildings, supporting transformers below 1000kVA.
• GGD2 Main Incoming Cabinet: Medium-sized manufacturing plants, shopping malls, office buildings, standard industrial distribution rooms with 1000~2000kVA transformers.
• GGD3 Main Incoming Cabinet: Large heavy industry factories, data centers, central substations, photovoltaic energy storage stations, high-rise complexes with high-current load over 2000kVA transformer.

7. Operating Environment Requirements

1. Ambient temperature: -5°C ~ +40°C, average temperature within 24 hours shall not exceed +35°C.
2. Altitude: No more than 2000 meters above sea level.
3. Humidity: Relative humidity ≤50% at +40°C; ≤90% at +20°C, no condensation inside cabinet.
4. Installation condition: Indoor dry and ventilated place, no corrosive gas, flammable dust and severe vibration; cabinet vertical tilt not over 5°.