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MDP Digital Time Overcurrent Relay GE Power Management
2 OPERATING PRINCIPLES GEK-100682D
2
2.6 INSTANTANEOUS UNIT
The multiple of pickup TOC measurement is compared, independently for each phase and ground, with a user
set value. If the set value is exceeded, a Pickup LED is turned on and a user programmable timer is started.
When the timer times out, the relay trips and a Trip LED is turned on. The trip level is user adjustable indepen-
dently for phase and ground. Likewise, the timer can be programmed, independently for phase and ground,
between 0.0 and 1.55 seconds, in steps of 50 ms steps. The instantaneous unit can be disabled by setting the
trip value multiplier to zero.
2.7 CHANGING SETTINGS
DO NOT CHANGE SETTINGS WHILE THE MDP IS IN OPERATION AND ITS PROTECTIVE ELE-
MENTS IN USE. TAKE THE RELAY OUT OF SERVICE BEFORE MAKING ANY SETTING
CHANGES.
Settings can be changed by DIP switches on the front of the relay. Once the desired changes are made, the
relay has to be initialized. Initialization is accomplished by depressing the reset lever for three seconds until the
Ready LED goes out.
Any time a dip switch is changed, the Ready LED begins to flash twice per second. If the settings are returned
to their previous positions, or if the relay is initialized by holding the reset lever for three seconds, the Ready
LED will stop flashing but remain lit. If the relay settings are changed and the relay is not reset, it will continue
to flash for three minutes, then it will accept the new settings and self-initialize.
Pickup current setting changes take effect immediately, altering the TOC and IOC elements, and
could cause the relay to trip; this is unlike other types of changes, where the flashing of the Ready
LED indicates that a change has been made but not yet finalized. Initializing the relay by pressing the
reset lever will return the Ready LED to an ON condition.
WARNING
NOTE
Courtesy of NationalSwitchgear.com
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