These controllers are for use with squirrel cage motors, 30 horsepower or less, 600 volts or less, across-the-line type starting. They are not intended as a substitute for the series M100 and M300 main fire pump controllers and must be acceptable to the authority having jurisdiction. Limited Service Controllers are withstand rated and listed by Underwriters' Laboratories, Inc., and Factory Mutual. Construction of these controllers differs from the main controllers in that the manually operated isolation switch is not required and that the circuit breaker is of the thermal-magnetic type and approved for disconnect purposes.

The M30 Series Combined Manual and Automatic Fire Pump Controllers utilize both Manual and Automatic motor start. Automatic starting may be intiated by the built-in pressure swich, deluge valve switch, or supervisory power failure. Manual starting is provided by a start pushbutton on the controller, remote manual start switch or by operation of the emergency start lever. A latch is provided on the lever which permits contiuous running of the motor until manually stopped.

The M30A controllers may be set for either automatic or manual stop after an automatic start. If automatic stop is specified, a running period timer is incorporated which keeps the motor running for a pre-set period of time and prevents too frequent starting and stopping in event of momentary actuation of the demand switch.