3-8 MIB High Impedance Bus Differntial Relay GEK-106426B
3.3 WIRING 3 HARDWARE
3
3.3.3 AC CURRENT TRANSFORMER INPUTS
MIB current inputs are composed of four elements:
1. Stabilizing resistor (inside HID).
2. Varistor (inside HID)
3. Contact from latching relay (inside HID)
4. Current input in the high-speed overcurrent module.
Depending on selected MIB model, the inputs configuration of High Impedance Device may change. If the Number of
High Impedance Differential Elements is 1, the HID will have only one input, If the Number of High Impedance Differential
Elements is 2, the HID will have two inputs, and If it is Bus / machine application it will have three inputs.
Figure 3–7: MIB CURRENT INPUTS
Current flows through stabilizing resistor into current input of the overcurrent module. Once high-speed overcurrent
module trips, latching relay contacts short-circuit stabilizing resistor plus current input. In this way, excessive heating
causing damage to resistors is avoided. MOV is used to avoid overvoltages damaging current input, limiting voltage to
1900V.
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