According to the attached table extracted from the Micrologic P user manual, in some cases you might need an external 24Vdc power supply and in other cases you won't. On the first row, you will find the circuit breaker status (Closed/open) and on the second row, you will find the AC supply to the Micrologic. You will only need a 24Vdc supply when the circuit breaker is OPEN and no power is being supplied to the Micrologic trip unit (last column in the table). In the previous two columns, it's a bit different. The explanation is as follows:

1. When the "status=CLOSED" and the "AC Power present for Micrologic P= YES", then this implies that a PTE (external voltage input) option is being used which enables the control unit to draw power directly from the distribution system upstream of the circuit breaker...this voltage input will supply the Micrologic even if the breaker is OPEN. In this case, NO NEED to have an external 24Vdc power supply.

2. When the "status=OPEN" and the "AC Power present for Micrologic P= NO", then this implies that there is no PTE option and in this case the 24Vdc power supply is needed to display the Contact Wear on the LCD of Micrologic.

Released for: Schneider Electric Saudi Arabia