Asco 4820, User Manual, Page: 46 / 51

Appendix
Load Bank Troubleshooting Guide
A-3
PROBLEM
POSSIBLE
CAUSES/REMEDIES
5. Load step(s) cannot be
energized.
a. A blower failure exists. (See problem 2.)
b. MASTER LOAD Switch is inoperative.
c. Control power is inadequate.
d. Fuse is blown in Load Bank control circuit or individual
branch circuit load fuse (if so equipped) is blown.
(Check and replace as required.)*
e. Blower Fail Relay is malfunctioning.
f. Load step switch is inoperative.
g. Load step contactor is inoperative.
h. Magnetic contactor has an open coil.
i. Load step resistor is open.
6. Contactor "chattering"
exists.
a. Contacts and/or core are dirty or corroded.
b. Connections to contactor coil are loose.
c. Control circuit line voltage is too low.
7. Load Bank or load step
does not give rated load.
a. Applied load voltage is either derated or inadequate.
b. Contactor does not close properly.
c. Load step resistor element is open.
d. One of the individual load branch circuit fuses is blown (if
so equipped).
*When checking fuses for continuity, be sure to remove all fuses from clips (in
fuseblock or Disconnect Switch). Test each fuse individually, out of circuit. (If
tested in circuit, there is the possibility of feedback which causes false readings. A
blown fuse may still check out OK.)