The trip circuit current is monitored by providing a current threshold detector in series with each Form-A contact. The monitor will set a flag at approximately 15-20 mA. The name of the FlexLogic™ operand set by the monitor consists of the output relay designation, followed by the name of the flag; e.g. Output H1 Current On. In most breaker control circuits, the trip coil is connected in series with a breaker auxiliary contact used to interrupt current flow after the breaker has tripped, to prevent damage to the less robust initiating contact. This can be done by monitoring an auxiliary contact on the breaker which opens when the breaker has tripped, but this scheme is subject to incorrect operation caused by differences in timing between breaker auxiliary contact change-of-state and interruption of current in the trip circuit. The most dependable protection of the initiating contact is provided by directly measuring current in the tripping circuit, and using this parameter to control resetting of the initiating relay. This scheme is often called "trip seal-in".
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