Gardner Denver ELECTRA-SAVER II Service Manual page 18

two-probe high discharge temperature switch have an
indicating pilot light mounted in the control box door. The
amber lighted ON indicates compressor running under
Constant Speed Control Under Automatic Start/Timed
stop the compressor may be stopped with the amber light
ON indicating power on The blue lighted LOAD indicates
compressor is loaded
To replace the bulbs in the pilot light (replacement bulb
number is Sylvania 120 PSB or equal
1.
Turn power off at main breaker panel
2.
Open control panel
3. Turn slotted locking screw on upper side of pilot
light body counterclockwise 1/4 turn and remove
the body from the lens holder.
4. Remove old bulb located in the body and insert
new bulb
5.
Reassemble body to lens holder and secure by turn-
ing locking screw 1/4 turn clockwise
ON-OFF SWITCH (Figure 2-1) – Early model Constant
Speed units with Low Demand Mode switch and the units
with Automatic Start/Timed Stop with Low Demand Mode
have an ON-OFF push button with an amber lighted section
to indicate ON (compressor running) and a green lighted
section to indicate LOAD (compressor loaded). The red
bar on the bottom of the ON-OFF switch is the OFF and
RESET on the Constant Speed unit with Low Demand
Mode The black bar on the bottom of the Automatic Start/
Timed Stop ON-OFF switch is the RESET.
To replace the bulb (Sylvania
120 PSB
or equal in any of
the switches
1.
Turn the power off at the main breaker panel
2. Open the control panel.
3. Turn the slotted locking screw on the upper side of
the switch body counterclockwise 1/4 turn and re
move the switch body from the switch operator.
4.
Remove the old bulb located in the stem of the switch
body and insert the new bulb
5. Reassemble the switch body to the operator and lock
in place by turning the locking screw 1/4 turn clock-
wise.
LOW DEMAND MODE SWITCH (Figure 2-1) – The
low demand mode switch when turned to the ON POSi
tion will blow the reservoir down when the compressor
unloads When switch is turned to OFF, unit will retain
pressure in reservoir when unloaded
~WARNING
The low demand mode switch CANNOT be used with
remote elevated oil coolers These units require special
wiring diagrams — check with factory.
SAFETY DEVICES –
these safety device%
Both control systems incorporate
Motor Protection Devices — Overload heaters are fur-
nished for the air-cooled oil cooler fan motor starter in
the voltage range specified There are three (3) overloads
of proper size for the starter and its enclosure. When re
placing or changing overloads be sure to select them from
a 3-overload heater table since the use of a third overload
derates each overload for a given enclosure due to the
extra heat An overload from a 2-overload heater table
would be undersize
The overload heaters are in a common overload block in
the starter and have a single common percentage adjust-
ment knob with a 90 to 1 10% range. The knob is set at the
factory on the 100% mark
Main unit starter should be adequately fused and provided
with overload heaters suitable for the application to pro
vide protection for the unit drive motor.
High Discharge Temperature Switch — Later Models
— Later models of the compressor unit are protected from
high discharge temperature by a two-probe adjustable
switch. One probe is located in the discharge pipe between
the compressor and the oil reservoir to sense compressor
discharge air/oil mixture temperature. The second probe
is located in the final discharge manifold and senses the
temperature of the air at the oil separators The switch is
located inside the control box (Figure 2-l); the shutdown
temperature is set on the adjustable dial If the temper-
ature of the air at either of the probes exceeds the tem-
perature set on the dial the switch will stop the unit Press
reset button of the Start/ Stop(On-Off) switch then the Start
(On) button to restart the unit
CAuTION
This adjustable switch dial must not be set higher
than
225° F.
DO not continue to reset the circuit if the same mal-
function occurs within a short period of time Find
and correct the trouble before resuming operation
In addition to protecting the unit from damage or failure
resulting from high air temperature, the switch also in
corporate four (4) indicator lights which show the point
of high temperature and/or the condition of the tempera
ture probes This information is shown on the decal inside
the control box and in Figure 2-4.
The High Air Temperature Switch may be checked period
ically to assure proper operation To check with the unit
running turn the dial on the switch to the temperature in-
dicated by the discharge temperature gauge. Unit should
shutdown If it doea not check the temperature gauge
accuracy and indicator lights— refer to the condition decal
on the control box door for the malfunction After opera-
tional check always reset switch dial to the proper setting
(225° F.).
Automatic Blowdown Valve — A pilot-operated valve
piped into the oil reservoir final discharge manifold ahead
of the check valve and connected to the unloader solenoid
valve which is wired into the motor control circuit will
release pressure from the oil reservoir each time the unit is
unloaded with low demand mode switch ON or when unit is
shut down. The blowdown line is equipped with a muffler to
reduce air discharge noise.
13-9-630 Section 4 Page 2