variation monitor

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A device that (a) senses deviations of any measured variable, such as voltage, current, frequency, or optical fiber diameter, and (b) is capable of initiating a programmed action, such as transferring to other power sources, transferring to other control devices, adjusting a control device, halting operations, or sounding an alarm, when programmed limits of the measured variable are exceeded, i.e., the departure from the nominal value exceeds a specified value. Note: An example of a variation monitor is a device that (a) monitors a voltage source, (b) disconnects the source if the voltage level changes by a specified amount, (c) reconnects the load to another voltage source, (d) turns on a red light, and (e) sounds a buzzer. Thus, proper power level continuity is assured and attendants are notified if unacceptable variations or monitoring system failures occur. See alsoalarm sensor, connection, control, current, device, disconnect, event, failure, frequency, initiate, level