Power Line Fuse Replacement; Circuit Breaker - Lakeshore 642 User Manual

Lake Shore Model 642 Electromagnet Power Supply User's Manual
ACCESS COVER CURRENT SETTING DIAL
Figure 7-3. Circuit Breaker
7. If incorrect, use a small straight blade screwdriver to reset according to Table 7-1.
8. Close the circuit breaker access door.
9. Replace the power wiring access panel using all perimeter screws.
7.5

POWER LINE FUSE REPLACEMENT

The Model 642 uses a low-power, start-up power supply to provide power to the main contactor coil through multiple
thermal safety switches. The start-up supply is energized any time the three-phase power input voltage is connected to
the Model 642. This section deals with the fuses for this supply. If the power line fuses for this supply are open, the
Model 642 internal three-phase contactor will not close and normal operation will not be possible. If the Model 642 is
connected to an input voltage that is higher than the selected voltage of the Model 642, these fuses are expected to clear
and prevent operation of the Model 642. Proper voltage selection must be made before connection to the power mains.
Access to these fuses is through the power wiring access panel.
WARNING: To avoid potentially lethal shocks, turn off the power supply and disconnect it from AC power before
performing this procedure.
CAUTION: For continued protection against fire hazard, replace only with same fuse type and rating specified for
the line voltage selected.
Use the following procedure to change the power line fuses.
1. Identify the power wiring access panel on the rear of the Model 642.
2. Turn the front panel line power switch OFF (O).
3. Disconnect the power cable at the plug end for safety.
4. Remove the perimeter screws holding the power wiring access panel.
5. Locate the two fuse holder assemblies as shown in Figure 7-1 and detailed in Figure 7-4
6. Pull open the access door to remove a fuse.
7. Check the fuse for continuity. Replace fuse(s) if necessary. Fuses should be replaced in pairs. Fuses are inserted
small-end first as shown.
8. Close the fuse access door(s).
9. Replace the wiring access panel using all perimeter screws.
7-4 Service