Vanguard MCCB-250 - Manual (Page 13)

REV 2 MCCB-250 USER’S MANUAL
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3.0 OPERATING PROCEDURES
3.1 Testing the Time Delay of a Protection Relay
Figure 3 illustrates a typical connection of the MCCB-250 to a protection relay to test its “Open
Time Delay”. The MCCB-250 injects a test current through a bus. The test current is sensed by
the CT of the protection relay. One of the relay dry contacts is used to stop the MCCB-250
timer.
Figure 3. Typical MCCB-250 Application