Hobart 100D20 Operation And Maintenance Manual With Illustrated Parts List page 121

OM-2032 / Operation and Maintenance Manual
100D20 / Generator Sets
Protective Circuit (Continued)
Trouble, Symptom & Condition
3. Load contactor opens during
power delivery. Overfrequency
indicating light (DS 40) ON.
4. Load contactor opens during
power delivery. Under-
frequency light (DS39) ON.
5. Load contactor opens during
power delivery. Overload
Indicating light ON.
March 28/94 Revised
Probable Cause
a. Electric governor
improperly adjusted, or
malfunctioning.
b. Governor improperly
adjusted.
c. Electric Governor System
Malfunctioning.
d. Defective
over-under-frequency
sensing module (K27).
a. Electric governor
improperly adjusted, or
malfunctioning.
b. Governor Improperly
adjusted.
c. Electric governor system
malfunctioning.
d. 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 transformer is
open Circuited.
c. Overload device printed
circuit board defective.
Corrective Action
Proceed as follows:
Adjust in accordance with Sect.
2-3, Para. 3, E, (3).
Check and adjust or repair in
accordance with ENGINE AND
CONTROLS Troubles 8 and 9.
If overfrequency nuisance
tripping continues after governor
system is proven to be good, and
an overfrequency condition does
not exist, replace over-
underfrequency module (K27), or
complete protective relay tray.
Proceed as follows:
Adjust in accordance with Sect.
2-3. Para. 3, E, (3).
Check and adjust or repair in
accordance with ENGINE AND
CONTROLS Troubles 8 and 9.
If overfrequency nuisance
tripping continues after governor
system is proven to be good, and
an under frequency condition
does not exist, replace over-
under frequency module (K27), or
complete protective relay tray.
Observe ammeter ( 5, Fig. 1 ).
Check for abnormal overload
condition and correct. If overload
device functions too open the
load contactor when an overload
does not exist, proceed to step B.
An open resistor will cause a
higher than normal Voltage.
Check Resistors (Sect. 1-1; 1,
Fig. 15). Replace if defective.
Check voltage at terminal E, Fig.
6. It it's 12-V DC, replace
overload device (K4)(Section
1-1; 7, Fig. 15).
Chapter 3-1
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