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Over-Temp switch or Over-Temp auxiliary relay is malfunctioning or not operating correctly.
Air switch high pressure intake tubing obstruction. Remove, clean and replace tubing as
necessary.
6) Wrong Voltage Lamp Illuminated (dual voltage units).
Over voltage fault indication on HMI screen: Input power voltage is higher than allowed
tolerances.
Under Voltage / Phase Loss / Phase reversal fault indication on HMI display: Input power
voltage is lower than allowed tolerances or one phase is missing or input phase is reversed.
7) Load Dump On indication on HMI screen.
Indicates that all load steps are removed because load dump toggle switch is operated.
8) Resistor Open or Phase Imbalance.
Blown load step fuse in branch load circuit (check and replace as necessary).
Loose bus bar or loose connection at resistor terminal or fuse (tighten all bus bar and
connection points as required).
Resistor element failure and burned open (replace as necessary).
9) Load Step or Load step application circuit cannot be energized.
Blower Failure, Air failure, Over-Temp, Wrong Voltage, Motor Overload, Load Dump, (see item
2 thru 8 above).
Load Dump switch is operated. One or more of the branch circuit load step fuses for the load
step in question is blown (check and replace as necessary).
One or more of the load step resistor for the load step in question has failed or burned open
(check and replace as necessary).
Load step contactor has failed or is inoperative due to loose connection or failed-open coil.
10) Load Step energized without rated load, or un-balanced load.
Applied main input bus voltage from power source under test is de-rated, low, imbalanced or
inadequate.
Contactor failure or not closing properly. Loose connection.
One or more of the branch circuit load step fuses for the load step in question is blown (check
and replace as necessary).
One or more of the load step resistor for the load step in question has failed or burned open
(check and replace as necessary).
11) Load Step contactor or relay chattering.
Contacts are pitted or oxidized.
Magnetic core and coil are dirty or corroded.
Coil connections to the contactor are loose.
120 VAC control circuit line voltage is low and/or inadequate.
12) Switchgear Circuit Breaker trips or Main Disconnect fuses are blown.
Fuses and/or circuit breaker trip settings are undersized.
A short circuit exists at the Load Bank Resistor (main input load bus or blower circuit).
A short exists in the power conductors feeding the Load Bank Resistor. Note: When checking
fuses for continuity, remove all fuses from fuse blocks, bus bars, fuse holders, and disconnect
switch. Test each fuse individually and out of circuit. A blown fuse left in the circuit may check
out OK with false reading of continuity due to feedback and return paths within the
