29
3.9 MOTOR AMPS OUTPUT
An output of the average RMS current in the three motor phases
is provided for connecting to a programmable controller. Unlike
conventional schemes which give an indication of only one
phase current, the Protect 4A relay can monitor all 3 phase cur-
rents simultaneously without the need for additional current
transformers. The output of 4-20 mA corresponds to motor cur-
rent from 0 amps to the full load current of the CT, For example,
if 100:5 phase CTs were used, the linear output of 4-20 mA
would correspond to phase currents of 0-100 amps. Under over-
load conditions the current is limited to 30 mA maximum.
For online monitoring the output can be used to drive a pro-
grammable controller or chart recorder with a linear 4-20 mA
input range. Useful applications include load studies and com-
puter control of loads.
Summary of Contents for PROTECT 4A-120
Page 1: ...MOTOR PROTECTION RELAY INSTRUCTION MANUAL ...
Page 5: ...2 FIGURE1 1 PROTECT 4A TYPICAL SYSTEM CONNECTION ...
Page 11: ...8 FIGURE 2 2 PHASE CT DIMENSIONS FIGURE 2 3 GROUND FAULT CT DIMENSIONS ...
Page 21: ...18 FIGURE 3 1 FRONT PANEL LAYOUT ...
Page 35: ...32 FIGURE 4 1 SINGLE PHASE INJECTION TESTING FIGURE 4 2 100 AMP CURRENT SOURCE ...
Page 39: ...36 FIGURE 4 3 GROUND FAULT EARTH LEAKAGE TEST ...
Page 44: ...41 FIGURE 5 1 HARDWARE BLOCK DIAGRAM ...
