Loss of Multiple Phases

Do not use either minimum voltage protection or voltage unbalance protection to determine the loss of multiple phases.

• The internal voltage power supply requires voltage of two phases to operate. (The voltage power supply has an operating range from 100 V to 690 V.)

• In circuit configurations 1 (Figure 103), 2 (Figure 104) and 3 (Figure 105), when multiple phases are lost the trip unit will measure the system voltage of the remaining phase on all three phases. For example, if two phases are lost on a 480 V three-phase delta system, the trip unit will meter 480 V_LL on all three phases.