Hobart 60PL20 Operation And Maintenance Manual page 97

TROUBLE, SYMPTOM
AND CONDITION
PROTECTIVE CIRCUIT (CONTINUED)
4. Load contactor
opens during power
delivery. Under-
frequency light ON.
5. Load contactor
opens during power
delivery. Over-
frequency indi-
cating light ON.
December 31/91 Revised
PROBABLE CAUSE
A. Electric governor
improperly adjusted,
or malfunctioning
(1) Governor improp-
erly adjusted
(2) Electric governor
system malfunc-
tioning
B. Defective over-under-
frequency sensing
module (K27)
A. There may have been
an overload condition
which caused the
overload device (K4)
to function normally.
B. One of the resistors
(R26, R27, or R28)
across overload
transformers is open
circuited.
C. Overload device
printed circuit board
defective
TEST, CHECK, AND/OR
REMEDY
A. Proceed as follows:
(1) Adjust in accordance
with Sect. 2-3, Para. 3, E, (3).
(2) Check and adjust or re-
pair in accordance with
ENGINE AND CONTROLS,
Troubles 8 and 9.
B. If overfrequency nuisance
tripping continues after the
governor system is proven to
be good, and an underfrequency
condition does not exist, replace
over-under-frequency relay.
A. Observe ammeter (3, Fig. 1).
Check for abnormal overload
condition and correct. If
overload device functions to
open the load contactor when
an overload does not exist,
proceed to step B.
B. An open resistor will cause
a higher than normal volt-
age. Refer to Schematic/
Connection diagram for exact
location of these resistors
Check resistors. Replace if
defective.
C. Replace overload module (K4)
(Sect. 1-1; 5, Fig. 7) with
an overload module known to
be operating properly.
OM-2053
3-1
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