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Tektronix A6901
Ground Isolation Monitor
Tektronix A6901 Ground Isolation Monitor

Produced from 1981 to (?)

Manuals – Specifications – Links – Pictures

The Tektronix A6901 Ground Isolation Monitor connects between mains power and test equipment without connecting protective ground, in order to safely allow referencing measurements to a low voltage instead of ground, or break ground loops.

It monitors the floating equipment ground voltage. If the voltage exceeds 40 V peak, or ground current exceeds a selectable limit of 0.5, 3.5 or 5 mA, the A6901 disconnects mains power and grounds the test equipment.


DC trip voltage 28 VRMS (40 V peak) or ±40 V DC
Current trip ±0.5 mA, ±3.5 mA and ±5 mA max. selectable
Trip delay <200 ms
Line voltage 90-128 V; 180-250 V; 48-66 Hz
Load power 500 W max.
Operating principle (click to enlarge)