Multilin 469 Motor Management Relay ... - GE Digital Energy

A: APPENDIX
• Programming the START INHIBIT settings to “On” makes a restart possible as soon
as 62.5% (50 × 1.25) thermal capacity is available.
• After two (2) cold or one (1) hot start, the thermal capacity used will approach
100%. The thermal capacity used decays exponentially (see Motor Cooling on page
5–55 for details). As such, the thermal capacity used after 1 time constant will be
37%, meaning there is enough thermal capacity available for another start.
Program 300 minutes (5 hours) as the COOL TIME CONSTANT STOPPED settings.
Thus, after two (2) cold or one (1) hot start, a stopped motor will be blocked from
starting for 5 hours.
• Since the rotor cools faster when the motor is running, a reasonable setting for the
running cool time constant might be half the stopped cool time constant or 150
minutes.
469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL A–5