Electrical Operation; Control System Description - Vulcan-Hart EF3 ML-52099 Service Manual

EF SERIES GAS FRYERS
CONTROL SYSTEM
DESCRIPTION
1. The thermopile (PG) provides the total
control voltage for this system.
A. One side of the thermopile is
connected to the common (C) of the
high limit (HL).
B. The other side of the thermopile is
connected to the normally open (NO)
contacts of the high limit.
C. The common of the high limit (below
the high limit trip temp.) is connected
through the normally closed (NC)
contacts of the high limit, through wire
3 to the combination valve pilot
connection common.
D. The other side of the pilot valve is
connected through wire 4 to wire 1 to
the high limit normally open contacts
which hold the pilot valve open.
1) If the high limit trips, connection is
made from the common to the
normally open contacts, turning
off pilot valve voltage. The gas
valve closes.
2. Thermostat Control.
A. One side of the millivolt supply is
connected through the high limit
system, as described above, to the
thermostat common (wire 3) of the
combination valve.
B. The other side of the thermopile is
connected from the normally open
contacts of the high limit to the
thermostat through wire 1.
F35641 (02-05)

ELECTRICAL OPERATION

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C. When the thermostat calls for heat
(closed circuit) power from the
thermopile is then connected to the
other combination valve thermostat
connection through wire 2.
D. If the high limit trips, the thermopile is
connected across zero ohms, the
output voltage of the thermopile drops
to 0.0 millivolts, and the thermostat
coil of the combination valve drops
out, shutting the thermostat valve.
3. Total Shutdown.
A. When the high limit trips, 0.0 millivolts
will read across both coils of the
combination valve, causing both
valves to close.
B. Pilot relight cannot be accomplished
until oil cools sufficiently to allow high
limit to close.
C If any wire in the system is cut or
broken, the system will shut down.