Variation Monitor

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