Element Control Switch - Market Forge Industries ST-E Service & Parts Manual

ELEMENT CONTROL SWITCH

ELEMENT CONTROL SWITCH
The Element Control Switch, located under the removable front
lower panel, just left of center, governs the flow of current to the
heating elements to maintain cylinder pressures at a near—constant
14 PSI
HOW IT WORKS
A copper tube extending from the top of the cylinder to the rear
portion of the Element Control Switch constantly reflects internal
cylinder steam pressures upon the built-in bellows of the Element
Control Switch to cause it to open or close an electrical circuit to the
contactor coil With little or no pressure applied to the bellows, the
circuit to the contactor will be closed, and providing the timer is set
to cycle, the contactor will click in and current will flow to the heating
elements When the pressure rises to 14 PSI (ongional factory
setting), the bellows will be sufficiently compressed by the steam
back-pressure to break the circuit to the contactor coil, the contactor
will click out, and current flow to the heating elements will cease
When cooling allows the pressure to drop below 13 Ibs, the bellows
will again complete the contactor coil circuit, activate the contactor to
click in, and allow the heating elements to energize Thus, by
working intermittently to open and close the contactor coil circuit, the
Element Control Switch, in effect, regulates current flow to the
heating elements
DIAL ADJUSTMENT
Two dial settings determine the operational range of the Element
Control Switch The larger dial (D) determines the maximum build-up
of cylinder steam pressure while the smaller dial (E) governs the
range of differential between the switch's cut-in and cut-off points
PRESSURE CONTROL SWITCH (BARKSDALE)
Models built after September 1980 use 2 Barksdale Pressure
Switches in place of the White-Rodgers Element Control
Switch and the Timer Control Switch
OPERATING PRESSURE ADJUSTMENT (BARKSDALE)
The operating pressure is determined by setting the right
switch (A) at approximately 10 PSI and the left switch (B) at
approximately 14 PSI Both switches were set at the factory
These settings can be verified by looking through the slot (in
the Red Rectangle) and observing the alignment of the black
line inside with the white scales on either side of the slot
To readjust turn the white knurled knob in appropriate
direction to raise or lower pressure
TIMER CONTROL SWITCH
Should a lower cylinder cooking pressure be desired, adjust the
larger dial (D) by inserting a screwdriver into the slot (B) found at its
center and turning it slightly counterclockwise to lower the pressure
Clockwise rotation will increase the pressure. Pressure must not be
adjusted to exceed 14 Ibs as the safety valve is set to automatically
open just above this point
The cut-in and cut-off points of the Element Control Switch may be
adjusted by rotating the small screw at the center of the smaller dial
(E) Normal factory setting is for a one pound differential between
cut-in and cut-off To increase the range of differential, rotate screw
clockwise, to decrease the range of differential, rotate the screw
counterclockwise Check adjustments through a trial cycle by
observing pressure gauge reading when contactor clicks out at
maximum cylinder pressure and again when it clicks in after cylinder
cooling The difference in pressures as read on the pressure gauge
should, at these points, be approximately one pound
RECALIBRATING ELEMENT CONTROL SWITCH
The Element Control Switch may be recalibrated should it vary
somewhat, through usage from its original factory setting
At the precise moment of contactor "click-out", the dial setting of the
Element Control Switch and the steam pressure gauge reading
should both be 14 Ibs A slight override of steam pressure build-up
will normally occur and indicate itself on the pressure gauge after
the contactor has "clicked-out" This is normal and is not to be
interpreted as an Element Control Switch out of calibration
WARNING Because power must be on to adjust pressure
switches, be sure to protect against electrical shock
Check adjustments through a trial cycle and observe
pressure readings on pressure gauge when switch (B) clicks
off at maximum cylinder pressure and when switch (A) clicks
on after cylinder cooling Making adjustments as needed
being careful not to let switch (B) pressure be set to exceed
14 Ibs Since the safety valve is set to automatically open just
above this point
RECALIBRATING PRESSURE CONTROL SWITCH
The actuation valve (differential) is factory set and cannot be
recalibrated
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