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> Schneider electric zelio® control measurement relays
Schneider electric zelio® control measurement relays
These devices detect when the current level on an AC or DC supply exceeds a pre-set threshold. They
have a transparent, hinged cover on the front face to prevent accidental alteration of the settings. This
Excitation control of DC machines
Controlling the load state of motors and generators
Controlling current drawn by a three-phase motor
Monitoring heating or lighting circuits
Controlling pump draining (undercurrent)
Controlling overtorque (crushers)
Monitoring electromagnetic brakes or clutches
The supply voltage is connected to terminals A1–A2. The current to be monitored is connected to
terminals B1, B2, or B3 (depending on the current range) and C. See the diagram below.
Hysteresis (h) is adjustable between 5 and 30%. For overcurrent,
h = (IS1 – IS2)/IS1; for undercurrent,
A measuring cycle lasts only 80 ms, allowing rapid detection of changes in current.
Overcurrent detection (RM4JA01 or selector on “>†for model RM4JA3•).
When the current level exceeds the threshold setting (IS1), the output relay is energized (with or without
a time delay, depending on the model). When the current returns to a value (IS2) below the threshold,
the relay is instantaneously de-energized. The value of IS2 depends on the hysteresis setting.
Undercurrent detection (selector on “<†for model RM4JA3• only).
When the current falls below the threshold setting (IS1), the output relay is energized (with or without a
time delay, depending on the model). When the current returns to a value (IS2) above the threshold, the
relay is instantaneously de-energized. The value of IS2 depends on the hysteresis setting.
