Hitachi America, Ltd., Industrial Systems Division, today announced the availability of the IPU-PSM option board. When installed in a Hitachi L300P Series inverter, the IPU-PSM adds Pump Sleep Mode functionality to the standard built-in PID function.
Standard PID control may, depending on system demand, allow a pump to operate at undesirably low speeds for prolonged periods of time. This can cause mechanical issues with certain pump types, and in general is a wasteful use of energy, since most pumps do not generate significant flow or head at low speeds.
The IPU-PSM allows for the specification of a lower limit on inverter output frequency. Should the PID function call for a frequency below that limit for a user defined period of time, the inverter will go to “sleep”, meaning the inverter output will shut off and the pump stops. The IPU-PSM continues to monitor the system pressure feedback via the inverter’s PID Deviation parameter. If system pressure drops below a defined level for a specified period of time, the inverter will “wake” and resume normal PID pressure regulation. In addition to this automatic operation, two digital inputs are available on the IPU-PSM: to force the inverter to wake, and to disable the sleep function.
The IPU-PSM is easily configured by means of four inverter parameter settings, and no additional hardware is required.