How to Use Milnor
®
Electrical Schematic Diagrams
PELLERIN MILNOR CORPORATION
Figure 7: Thermal Overload (ET)
Schematic Symbol Legend
.
A. Heater (one per phase)
B. Overload relay; contacts open if overload
condition exists
EX=Electrical Transformer (Figure 8)—A device that transfers electrical energy from one
isolated circuit to another, often raising or lowering the voltage in the process.
KB=Keyboard—Device similar to a typewriter for making entries to a computer.
MN=Electronic Monitor (CRT)—A cathode ray tube used for visual presentation of data.
MR=Motors (Figure 9)—Electromechanical device that converts electrical energy into
mechanical energy.
Figure 8: Transformer (EX) Figure 9: Electric Motor (MR)
MV=Motor (Variable Speed) Inverter—To vary the speed of an AC motor, the volts to
frequency ratio must be kept constant. The motor will overheat if this ratio is not maintained.
The motor variable speed inverter converts three phase AC to DC. The inverter then uses this
DC voltage to generate AC at the proper voltage and frequency for the commanded speed.
Note 2: Switch symbols used in the schematics and described below always depict the switch in its un-
actuated state.
PX=Proximity Switch (Figure 10)—A device which reacts to the proximity of an target without
physical contact or connection. The actuator or target causes a change in the inductance of the
proximity switch which causes the switch to operate. Proximity switches can be two-wire
(AC) or three-wire (DC) devices.
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