Winco MDS50R3/B - Manual (Page 8)

Page 6
b. High water temperature shutdown -(HWT)- The
engine coolant sensor temperature monitoring begins
immediately with the start signal. If water temperature is
excessive at time of start, (i.e. heat soak after shutdown),
the unit is still permitted to start. The ‘HWT’ condition is
permitted to exist for up to 60 seconds after the unit
initially starts before a shutdown WITH ALARM occurs. If
the excessive water temperature condition is corrected
within the initial 60 second period, the ‘HWT’ circuit
begins normal monitoring of the engine temperature and
the ‘safety shutdown’ circuit is reactivated. The ‘HWT’
signal is derived from a temperature gauge mounted in
the engine control panel.
c. Overspeed adjustment -(OS)- Overspeed protec-
tion is provided by a frequency sensing network within the
controller. The trip point of the frequency network is
adjustable via a rheostat located in the center of the
controller. The adjustment is accessed through the small
hole in the center of the engine control module.
NOTE: Use a plastic or non-metallic screwdriver when
making any adjustment to the overspeed. Clockwise
(CW) rotation increases the tip frequency, and thereby
raises the shutdown speed. The frequency input is
obtained from the engine battery charging alternator.
d. Overcrank -(OC)- The MDS85R is designed to
use cycle cranking. This feature provides a series of five
cranking cycles lasting 12 seconds with a 12 second rest
period between each. Failure of the engine to start by
the end of the fifth crank period results in an “overcrank”
shutdown and alarm indication.
3. Cranking Disconnect Signal
The cranking disconnect signal is obtained from the
frequency sensing network within the controller. The trip
point of the crank disconnect is not directly adjustable but
is a percentage of the overspeed adjustment.
4. E.C.M. - Program Notes
a. Loss of frequency input - In the event the input
frequency goes to zero (engine runs out of fuel, battery
charging alternator fails, etc.), the LOP shutdown circuit
is by-passed, and a 12 second wait period is initiated. If
frequency returns within this time period, LOP monitoring
resumes and operation continues normally. If frequency
has not returned at the end of this time period, the engine
oil pressure status is observed to determine whether the
engine is actually running or stopped. If the engine has
stopped (i.e.- air in fuel, etc., the unit is shut down with
an “overspeed” indication and alarm.
b. “Overspeed” indicator light can mean a loss of
control signal during the previous run period (i.e.- bat.
charging alternator belt broken).
TROUBLE SHOOTING HINT: This is of particular note
since the tendency is to pursue only overspeed faults.
The overspeed signal source (battery charging alternator)
is a key component in this system and must be checked
out thoroughly whenever an “OS” shutdown occurs.
Please note: The controller does not provide protection
against loss of signal during start-up. A shutdown with
alarm due to any of the above conditions will prevent any
subsequent operation of the generator set. The control
switch on the control panel must be momentarily placed
in the “off” position to reset.
E. VOLT/HERTZ VOLTAGE REGULATOR
The purpose of the voltage regulator is to maintain the
voltage output of the Generator Set within a specified
percentage of its rated output from no load to full load.
The voltage regulator controls the voltage output of the
main generator by regulating the amount of current
delivered to the exciter field.
1. Location -Access to the voltage regulator assembly
is gained by removing the control panel access door
located through the left rear housing door.
2. Description - The Basler model VR63-4C voltage
regulator is a completely encapsulated unit. The regulator
controls the DC exciter field voltage on brushless genera-
tors to regulate the output voltage. Regulation is provided
by sensing the generator output voltage, converting it to
a DC signal and comparing the signal to a reference
voltage signal. An error signal is developed and used to
control the DC field power in order to maintain a constant
generator output.
3. Operation of Voltage Regulator - The voltage
regulator has been installed in the Mobile Diesel Genera-
tor set and tested at the factory prior to shipment. No
additional set-up is required when changing from one
voltage to another. The only adjustment required is to
fine tune the exact voltage you want using the voltage
adjustment rheostat located on the front panel. The
adjustment range is 10% of the nominal voltage.
Some minor changes must be made for 50 cycle opera-
tion. Refer to 50 Hz operation later in this section for set-
up procedures.
a. During periods of operation at reduced speed use
the field circuit breaker to remove the power from the
regulator.
b. If the exciter field voltage exceeds 95 VDC, the
regulator senses over excitation and automatically
removes the field current after a time delay. This time
delay is inversely proportional to the magnitude of the
detected over voltage condition. At approximately 140
VDC, the field voltage is removed instantaneously.