HT Panels

Distribution systems utilizing HT distribution behave differently from low voltage distribution boards because one erroneous action can result in an entire section of a facility going down. Our HT Panels are designed for situations where switching, protection and isolation all function in a predetermined sequence and are not dependent on actions taken by an operator.

Panel configurations are finalized after studying the incoming supply configuration including; transformer rating, fault level, and feeder diversity. Types of breakers used, busbar ratings and insulation clearances are based on the data from a system over and above voltage class. Compartmentalized construction ensures that cable terminations, breaker operation and busbars remain physically separated; thereby allowing for safe maintenance.

The configuration of protection relays reflects actual conditions on the network such as overloads, short circuits, earth faults and feeder discrimination. The application of interlocking between breakers, isolators and earthing switches will help to prevent unsafe operations. The use of mimic indications and metering will be available to give a quick reading of the status on the system in the case of an emergency shutdown.

The internal heat of the panel enclosure and ventilation needs to be taken into account when designing the panel layout. There must also be sufficient space in the panel for bending the HT cable at the required bending radius and for the termination of the glands.

Routine testing of the panels will consist of insulation resistance testing, high voltage testing, breaker timing tests and relay secondary injection tests. These HT panels are being supplied for installation throughout the U.S., where dependable medium voltage control is required, quick fault clearance will minimize downtime, and safe isolation of the system will allow safe operation without interruption of power supply to customers.