GE 469 Instruction Manual page 317

CHAPTER 8: APPENDIX
469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL
• Programming the
START INHIBIT
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
5–56 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
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.
settings to "On" makes a restart possible as soon
COOL TIME CONSTANT STOPPED
settings.
8–5