Duty Cycles And Restarting - ABB MS116 Manual

MA N UA L MOTOR START ER G UI D E

4.2 Duty cycles and restarting

To avoid issues with nuisance tripping, manual motor starters should not be operated at an arbitrary operating fre-
quency. Applications involving up to 15 starts per hour are acceptable. Higher starting frequencies are acceptable if
the duty ratio is lower and the motor's making current does not appreciably exceed six times the full-load current.
The diagram below provides guideline values for starts-per-hour as a factor of the duty ratio (ON- vs. OFF-time) and
the time required to start the motor t .
a
Figure 24: Diagram of the duty cycles and restarting, Example: for a motor with a duty ratio of 60 percent and a start duration of 1 second, 40 starts per hour
are acceptable.
After tripping, the bi-metals need to cool down before the manual motor starter can be reset. The device handle will
not permit being switched to the ON position until this is achieved.
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