- Three Phase AC Systems

The CME420 measures for overcurrent and undercurrent in AC systems. Two seperate alarms allow for the simultaneous measurement of overcurrent, undercurrent, or the threshold between two values. The CME420 may be directly connected to systems up to 16 A. An external current transformer allows the unit to be connected to much higher current values.

Measurements taken are read as true RMS values; harmonics up to 460 Hz are taken into account. Each of the two alarms has a seperate Form C SPDT contact for use with external LEDs, contactors, PLCs, and many other applications. The two alarms may be set to overcurrent and/or undercurrent. Contacts may be set for normally energized or de-energized operation.

For systems greater than 16 A, the CME420 may be indirectly connected to the system via an X/5 current transformer. After entering the ratio value into the digital menu, setpoint values can be entered and current readings will be displayed as their true values up to 999 A. No ratio calculations are required.

The CME420 has three seperate, adjustable time delays (start-up, response, on release) from 0 to 99 seconds. Setpoint and hysteresis ranges allow for application-tailored sensitivity. A fault memory toggle allows alarms to either latch or auto-reset after it has cleared.

Values are read and settings are changed via a digital LCD display. Three pushbuttons allow for navigation through built-in menus. History memory stores the last received alarm. A password protection may also be set. The CME420 is a UL listed product.

These devices are suited for installation into standard distribution panels according to DIN 43 871 and for quick assembly onto support rail according to DIN EN 50 022 or for screw mounting.