Hobart 60PL20 Operation And Maintenance Manual page 26

OM-2053
(g) Fuse-interlock relay
The function of the fuse-interlock relay (8) is to interrupt the load contactor holding coil circuit
and remove the load in case of a "blown" fuse (8, Fig. 6) in the protective relay coil circuit.
(h) Auxiliary underfrequency relay
The function of the auxiliary underfrequency relay (9) is to automatically open the excitation-
deenergization relay and disconnect the voltage regulator any time generator frequency
drops to 380 Hz or below. This protects the voltage regulator PC board (13, Fig. 7) against
overload which could be caused by high voltage regulator output in its attempt to maintain
voltage when the generator is operating at a speed which cannot produce normal voltage out-
put.
NOTE: If the auxiliary underfrequency relay is tripped, it will be necessary to momentarily
place engine operating mode switch (5, Fig. 8) in BUILD-UP-VOLTAGE position to restore
generator voltage.
(j ) Terminal boards
Two terminal boards (14) provide connection facilities for small leads.
(k) Solid-state voltage regulator
This voltage regulator consists of two assemblies, a line-drop compensation assembly (17)
and a voltage regulator PC board (13). A full and working description of this voltage regulator
is provided in Solid State Regulator Manual OM-2020, which is a part of Chapter 6 of this
manual.
(l) Overload module (5)
See Para. 6, H, (3) for functional description of the overload module.
(m) Rectifier (10)
See Para. 6, H, (4) for functional description of the load contactor rectifier.
F. Engine Control Panel (See Fig. 8)
The engine control panel is mounted directly below the control box. Along with engine controls and in-
struments, generator output controls are mounted here. A plexiglas window in the canopy rear door,
slants outward at the bottom to form an opening for access to controls when the door is closed.
(1) Engine instruments
Engine operation is monitored by an ammeter (4) a coolant temperature gage (8), and an oil pres-
sure gage (10). An hourmeter (6) records engine operating time.
(a) Ammeter
The ammeter (4) indicates the direction and value of current flow in the 12-V DC electrical
system. Its graduated range is from -60 A through 0 A, to +60 A.
(b) Temperature gage
The temperature gage (8) is a mechanical type of unit construction. It consists of a panel
mounted indicating mechanism which is connected by a capillary tube to a bulb mounted in
the engine cooling system. The gage indicates engine coolant temperature in the range of
100F to 220F.
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December 31/91 Revised