GGD LV Switchgear

What Is GGD LV Switchgear?

GGD remains the most widely specified low-voltage cabinet in Chinese industrial and building projects because it delivers the required protection coordination at the lowest cost per cubicle. For export projects it is typically used as the incoming and feeder section of a package substation or a plant distribution room.

GGD is the fixed-design low-voltage distribution cabinet family used for receiving and distributing power at 400 V. It is the economic choice for buildings, workshops and plant distribution rooms where the outgoing circuits are fixed and frequent breaker replacement is not required. Each cubicle is assembled around a main air circuit breaker with rated currents from 400 A up to 3150 A, and a set of outgoing distribution breakers.

How It Works

The incoming cubicle carries the main breaker and the busbar system, while feeder cubicles carry the outgoing circuits with their protective devices. The busbar is tinned copper, sized for the cubicle rating, and the internal separation keeps the incoming and outgoing compartments apart. Protection and control devices are mounted on the cubicle mounting plate, and the door carries the operating handles and indication for each circuit.

• Fixed incoming and feeder cubicles assembled around air circuit breakers.
• Tinned copper busbar rated to match the cubicle current class.
• Outgoing circuits with moulded-case or air breakers for distribution and motor circuits.
• Reactive compensation sections available in the same line-up as an automatic capacitor bank.
• Enclosure protection IP30 / IP40 indoor; separate outdoor IP54 cabinets available.

Typical Applications

• Industrial plant main distribution and motor control centres
• Commercial building low-voltage switchrooms and apartment distribution
• Incoming and outgoing sections inside package substations
• Sub-distribution in workshops, offices and public buildings
• Auxiliary and standby circuits in mining camps and construction sites

How to Select

Begin with the calculation current of the largest outgoing feeder group, because the main breaker in the incoming cubicle has to carry it with the appropriate headroom. Then decide the withstand level — the short-time withstand current of the busbar and the breaking capacity of the main breaker must both sit above the design short-circuit current of the installation, and the two are often quoted in different units, which is where mistakes happen. Finally, list the outgoing circuits with their load type because motor circuits need a different breaker curve and more gland space than a lighting circuit.