As it is often important to ensure that machinery does not rotate in the incorrect direction, the inclusion of phase rotation protection within a motor protection relay makes good sense. In the case of NewElec motor protection relays that offer this protection it is achieved by measuring the incoming phase voltage. Thus it is not possible to start the motor should the incoming phases be reversed. There is no relay on the market that will provide such protection for phase reversal that happens at the motor terminal box.
Some of the NewElec motor protection relays do, however, permit software settings that allow the motor to start by reversing the phase measurement settings. This enhancement dispenses with the need of the electrician to physically reverse the phase measurement inputs of the relay.




