БАО

Emergency trip unit (БАО)

Purpose:

• The БАО supplies ВР1-type vacuum circuit breakers at transformer substations and in switchgear assemblies with a 220 V AC or rectified control supply.
• In normal operation the БАО supplies the vacuum circuit breakers from the auxiliary services transformer, or from an НТМИ-type instrument transformer with a 100 V winding, the voltage then being stepped up to 220 V by a БПН.
• With no control supply voltage present, the БАО charges the capacitor bank and maintains the voltage needed to trip the vacuum circuit breaker, drawing energy from the relay windings of one or two ТЛК-10 current transformers fed by the current in the outgoing lines.
• In the event of a short circuit in the outgoing lines with no control-supply voltage present — in the case where the short circuit was preceded by a state with no current or only a small current in the outgoing lines — the BAO provides rapid charging of the capacitor bank of the vacuum circuit breakers and generates a trip-enable command. The trip-enable command is generated by the BAO by closing dry contacts, provided that enough energy has been accumulated to trip the vacuum circuit breaker. The energy for charging the capacitor bank comes from the secondary windings of the current transformers fed by the current in the outgoing lines.

Datasheet for the БАО