Hobart 60PL20 Operation And Maintenance Manual page 31

(3) Overload module
The overload module is located inside the generator control box. This overload module (5, Fig 7)
is a solid-state device designed to interpret a signal from the current transformers and to send a
signal to the protective monitor module (7, Fig. 7) when an overload condition exists in any gener-
ator output phase. A pull-apart electrical connector is mounted on the owerload module to provide
quick-disconnect facilities for all wiring to the module. The overload module is equipped with a
hermetically sealed, reed-type relay. Relay contacts are normally open. The solid-state circuitry is
designed to close relay contacts when output current in ANY phase reaches 125% of normal
rated output capacity. The closed relay sends a signal to the protective monitor. This signal
"gates" the overload SCR (silicone-controlled rectifier) in the protective monitor and interrupts the
load contactor holding circuit, allowing the load contactor to open.
The following is a list of overload module characteristics:
NOTE: The overload protective system will function when any phase carries 123% to 127% of
rated load.
At 125% load the module will function in 4 minutes.
At 150% load the module will function in 16 seconds.
At 200% load the module will function in 4 seconds.
NOTE: All times are plus or minus 25% and are nonadjustable.
(4) Rectifier
A diode bridge rectifier is located inside the generator control box. (See Fig. 7, item 10) . This di-
ode-bridge rectifier receives 400-Hz AC from phase C of the generator output an converts it to a
pulsating, direct current for energization of the load contactor coil only. This DC coil-holding circuit
is controlled indirectly be controlling the 400-Hz AC to the rectifier. The ground circuit for the recti-
fier's AC supply must pass through the relay contacts in the protective monitor module to ground
cable N. Therefore, any time a protective device functions to open the protective monitor relay,
the rectifier's AC circuit is opened. No DC is then available for the load contactor coil, hence, the
load contactor opens.
December 31/91 Revised
OM-2053
1-1
Page 17