Electrical Power Systems Technology

430 Electrical Power Systems Technology

Figure 16-5 shows a circuit that is another method of motor-jogging
control. This circuit has a separate pushbutton (which relies upon an NO
contact [CR] to operate) for jogging. Two control relays are used with this
circuit.
The circuit in Figure 16-6 is a forward-reverse pushbutton control
circuit with both forward and reverse limit switches (normally closed
switches). When the “forward” pushbutton is pressed, the load will op-
erate until the “forward” limit switch is actuated. The load will then be
turned off, since the circuit from L1 to L2 will be opened. The reverse cir-
cuit operates in a similar manner. Two control relays are needed for for-
ward-reverse operation.
The circuit of Figure 16-7 is the same as the circuit in Figure 16-6, ex-
cept for the pushbutton arrangement. The forward and reverse pushbut-
tons are arranged in sets. Pressing the “forward” pushbutton automatical-
ly opens the reverse circuit, and pressing the “reverse” pushbutton auto-
matically opens the forward circuit. Limit switches are also used with this
circuit. Their function is the same as in the circuit shown in Figure 16-6. In
the circuit in Figure 16-7, when the “forward” pushbutton is pressed, the

Figure 16-5. A pushbutton control circuit for start-stop-jogging

Figure 16-6. A forward-reverse pushbutton control circuit with forward and re-
verse limit switches