Gardner Denver ELECTRA-SAVER II Service Manual page 22

capacity and pressure must be made with care This is a
finely balanced control and must be handled as such if
optimum performance is to be obtained from the unit
Operating Air Pressure Adjustment – Turn low demand
mode switch OFF. Start the unit Ciose the air service line
valve (furnished by customer, allow the unit to build to fuii
pressure and unload and proceed as follows
A iNLET VALVE SETTING — Should be 10 PSI above
compressor rating
Pressure Too High
1.
Loosen the inlet vaive subtractive pilot locknut
Back the adjusting screw out about one turn
2.
Open the air service valve and bieed air from the
unit so that compressor loads again Ciose the
valve and ailow the compressor to unload
3. Repeat Steps 1 and 2 untii the proper pressure is
obtained Tighten the locknut
Pressure Too LOW
1. Loosen the iniet vaive subtractive pilot locknut
2.
Turn the adjusting screw in until the proper
pressure is obtained
3. Tighten the iocknut
R SET RESERVOi R BLOWDOWN AND COMPRESSOR
UNLOAD.
1.
Turn the upper adjusting screw on the low demand
mode pressure switch untii the pointer on the left
edge indicates the desired pressure.
2. Adjust service valve untii unit is operating at full
load set point
3. Turn iow demand mode switch ON.
4. Close service valve. Note the air pressure when
unit biows down. if it is not the pressure desired
repeat Steps 1, 2, and 3 untii proper unload
pressure is obtained
C. SET COMPRESSOR LOAD POiNT.
1. With unit running air receiver at full pressure and
shop air iine vaive closed and iow demand mode
switch in the ON position set the iower (dif-
ferential adjusting screw on the low demand mode
pressure switch near the desired pressure Fuil
receiver pressure minus the differential is the
compressor ioad point The differential range is
approximateiy 2-18 PSIG on the circular scaie
above the adjusting screw. it should be set
approximately 10 PSiG.
2. Bieed air from the air rceiver and note the pressure
at which the compressor loads
3.
Repeat Steps 1 and 2 until desired low receiver
pressure point is obtained
CAUTION
DO NOT AdJUST THE FULL UNLOADED AIR
PRESSURE TO MORE THAN 10 PSIG HIGHER
THAN THE MAXIMUM STAMPED ON THE
UNIT NAMEPLATE
MINIMUM OPERA TING PRESSURE IS 65 PSIG
LOW DEMAND MODE CONTROL SYSTEM – The low
demand mode control system is suitabie for use only on
water-cooled or air-cooled units which have the oii cooier
moduie close coupled but not joined or having horizontal
remote (iocated on same ievel with compressor but at some
distance awayj mounting from the compressor unit main
base.
~WARNING
J!\ LOW DEMAND MODE CONTROL SYSTEM
CANNOT BE USED WITH A REMOTE OVER-
HEAD MOUNTED OIL COOLER
CONSTANT SPEED CONTROL SYSTEM WiTH LOW
DEMAND MODE –
This Controi system is used where
there is a demand for air with no long periods of nonusage
With compressor running with the iow demand mode switch
in the ON position the compressor will build to the set
pressure and unload and the air in the oii reservoir will blow
down
During the time the compressor is unioaded with the motor
running the unit draws only about 20% of the power
required on load at 100 PSIG.
With the low demand mode switch in the OFF
position, the
compressor oil reservoir wiil not blow down when the
compressor unloads
Electrical Wiring — Figures 12-4, 13-4, 14-4 and 15-4 are
the wiring diagrams for the units with Constant Speed
Control System
AUTOMATIC START/TIMED STOP CONTROL SYSTEM
WITH LOW DEMAND MODE— This control system is used
where the air requirements vary wideiy, change in fre
quency of demand and where it is desirabie to have some
degree of controi over the length of time the motor wiil run
after the compressor unloads
The Automatic Start/Timed Stop Controi System offers
three modes of operation controlled by turning the iow
demand mode switch and/or the timer Constant Speed
and Automatic Start/Timed Stop both with or without low
demand mode
Constant Speed Operation: When the iow demand mode
switch is in the OFF position the compressor will build to
full pressure and unload and continue to run unioaded
Automatic StarVTimed Stop Operation: When the low
demand mode switch is in the ON position and when the
timer is set between O and30, the unit wili start and the iniet
valve open when the pressure in the receiver falis to the
pressure switch low setting.
When the pressure rises to the pressure switch high
setting the unit will unioad (LOAD light off), the iniet valve
will close, the motor will continue to run and the oil reservoir
13-9-630 Section 4
Page 6