I need to be able to tell if a single phase motor/generator is operating as a motor or as a generator via some type of metering or sensing arrangement. (it can be acting as either at anytime)
Induction motors driven faster than their no load speed will operate as induction generators. The direction of current when motoring is backwards as to when it is generating so a simple directional relay will do the job. You can find devices to detect this at the BENDER website http://www.bender.org/
A current transformer (CT) and simple current transducer will give you this information. Current into the machine as a motor and current out of the machine as a generator. The CT will handle the voltage and current rating of the motor and convert to the rating of the transducer. The output of the transducer can go to an analog input or through some hardware logic into a digital input depending on your needs.
Responding to Andrew Lovelace's Mon, Nov 18, 3:40 pm, query:
The simplest suggestion is to install a bi-directional Wattmeter or two reverse connected Wattmeters. A second suggestion is to employ a Watt-measuring transducer, having the built-in current and potential transformers to provide bi-directional measurement. A third, but little more complex approach is to install two Hall-effect sensors, one for Volts, the other Amperes, connected to a calculation circuit. Contact a vendor of Hall-effect sensors for a suitable schematic.
Responding to Chuck Lennon's Sat, Nov 23, 4:10 pm, comments:
Amperes, alone, will not provide a watt measurement.
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