Frequently Asked Questions about 469-P5-LO-A20
What should the phase CTs, ground CTs, and motor full load current be set for the GE 469-P5-LO-A20 Relay?
For the GE 469-P5-LO-A20 Relay the phase CTs have to be chosen for the full load current at 50 percent to 100 percent of a primary CT, but with the full load current is 347.5A a 350:5, or 400:5 CT can be picked and the 400:5 is standard for the size that is selected. The high resistive grounding systems are senstive to ground detection and are possible with the 50:0.025 CT. Setting the motor full load current to 348A is specified by the other data sheets of the phase current transformers and ground current transformers.
What are the over load pick up and over load curve settings for the GE Motor Management Relay's?
The over load pick up setting should be on the highest service factor of 1.25 x full load current, so that the motor service factor is at 1.15 and if the service factor is unknown, then it should be automatically set to 1.0. This motor has resistance temperature detectors (RTDs) that the relay with be using to protect the over load pick up. For the over load curve to not compromise the protection on the relay, the over load curve should be set at the standard over load curve and to have the most process up time, it will be just below the cool thermal limit. Over load curve 7 is the best fitting for this relay.