AEC Colortronic MSH Series 2039 - Manual (Page 25)

C Series Granulators Maintenance 25 of 53
5-5 Testing the Interlock Switches
The cutting chamber and screen cradle interlock switches insure that the granulator cannot be
running when the cutting chamber or screen cradle are open. When disengaged, the
interlocks open the electrical control circuit to the motor and prevent the machine from
running.
If an interlock does not work, the complete mechanism, including the switch, must be
removed and disassembled to determine the cause of the malfunction.
Using and Ohmmeter to Test the Interlock Switches
Use the following procedure to test the interlock switches using an ohmmeter:
1. Turn the main power off, remove the line fuses, and tag the machine as out of
service.
2. Using the wiring diagram on page 50, locate the interlock switch terminal strip in the
jackscrew control panel. The wires for the upper chamber interlock switch are
numbers 1 and 16. The wires for the screen cradle interlock switch are numbers 16
and 5.
3. Connect an ohmmeter across each interlock switch terminal or across all interlock
switch terminals.
4. Switch the ohmmeter resistance to the lowest scale. When the interlock actuator bolts
are in place and properly activating their switches, the ohmmeter should read zero
resistance. When either or both actuator bolts are withdrawn, the ohmmeter should
read infinite resistance.
5. Loosen one actuator bolt 3 to 4 turns. If the meter reads infinity before the bolt can be
completely removed, the interlock is working. If the meter reads zero resistance when
the actuator bolt is completely removed, the interlock is not working.
6. Replace the first actuator bolt tested before testing the next one.
Manually Testing the Interlock Switches
With the cutting chamber and screen cradle closed and the power on, use the following
procedure to manually test the interlock switches:
1. Push the start button to start the granulator
2. Retract the screen cradle interlock actuator screw by turning it counterclockwise.
Make sure that the end of the actuator screw is visible and clear of any contact. The
granulator should stop. If the granulator does not stop, the interlock is not working.
3. Engage the screen cradle interlock actuator screw by turning it clockwise, and restart
the granulator.
4. Retract the cutting chamber interlock actuator screw by turning it counterclockwise.
Make sure that the end of the actuator screw is visible and clear of any contact. The
granulator should stop. If the granulator does not stop, the interlock is not working.
5. Engage the cutting chamber interlock actuator screw by turning it clockwise.