DSE Model 8620 Main Control and ATS Operators Manual
111
31
separate excitation
device
A device that connects a circuit, such as the shunt field of a synchronous
converter, to a source of separate excitation during the starting sequence.
32
directional power
relay
A device that operates on a predetermined value of power flow in a given
direction such as reverse power flow resulting from the motoring of a
generator upon loss of its prime mover.
46
reverse-phase or
phase-balance
current relay
A device in a polyphase circuit that operates when the polyphase currents
are of reverse-phase sequence or when the polyphase currents are
unbalanced or when the negative phase-sequence curr
value.
48
incomplete
sequence relay
A device that generally returns the equipment to the normal or off position
and locks it out if the normal starting, operating, or stopping sequence is not
properly completed within a predetermined time.
50
instantaneous
overcurrent relay
A device that operates with no intentional time delay when the current
exceeds a preset value.
51
ac time overcurrent
relay
A device that functions when the ac input current exceeds a predetermined
value, and in w
hich the input current and operating time are inversely related
through a substantial portion of the performance range.
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