HID High Impedance Differential Module

Product Description

Use the HID module in conjunction with a high-speedovercurrent relay to provide three phase high impedance differential protection for substation busbars of any voltage level. Additionally, it can also be usedto protect electrical machines like transformers, generators or motors againstrestricted ground faults.

Each HID module includes resistors that provide the associated high impedance relay with stability againstexternal faults, and varistors (MOV - Metal Oxide Varistors) in order to limit the secondary peakvoltage below 2 kV during fault conditions.

Use the auxiliary contacts provided by an optional latchingrelay to short-circuit the resistors once the associated relay has tripped, toprevent the fault current from circulating through the resistors.

The HID front panel incorporates a Reset pushbutton to resetthe latching relay once the fault has been cleared, in order to eliminatetheresistors short circuit.

Features & Benefits:

• Single-zone bus protection, reactor protection, or sensitive restricted earth fault protection on grounded, wye-connected power transformer windings
• Provides metal oxide varistors (MOV) to clamp secondary peak voltage to less than 2 kV