Pressure Switch Adjustment - Ingersoll Rand 2340 Manuel De L'utilisateur

PRESSURE SWITCH ADJUSTMENT

WARNING
High voltage is present at the pressure switch contacts when
the power supply is connected. Disconnect, lock and tag main
power supply before making adjustments.
CAUTION
Do not adjust the pressure switch to exceed the maximum
discharge pressure of the unit.
NOTICE
Adjust the pressure switch only if adjustments are absolutely
necessary.
CUT-IN & CUT-OUT.
The cut-out (compressor shut-down) is the pressure at which the
switch contacts open, and the cut-in (compressor restart) is the
pressure at which the switch contacts close. See COMPRESSOR
CONTROLS.
STANDARD PRESSURE SWITCH. The Standard NEMA-1 Pressure
Switch is Pre-set at the required pressures and the range and
differential settings ARE NOT adjustable. These Pressure Switches
should not be tampered with in any way and no attempt should be
made to adjust the pressure settings as this could damage the Switch
to the point of failure and/or void any warranty for the Pressure
Switches.
NOTICE
Some pressure switches are equipped with an on-off lever used
to open and close the electrical contacts inside the switch.
THIS LEVER IS NOT A DIFFERENTIAL ADJUSTMENT CONTROL.
The pressure switches with the on-off lever do not have a
differential adjustment control.
ADJUSTMENT PROCEDURES (ADJUSTABLE SWITCHES):
1. Remove the pressure switch cover.
2. Set the cut-in pressure with the range adjustment nut. Turn the nut
clockwise (in) to increase the pressure or counter-clockwise (out) to
decrease the pressure.
NOTICE
One full turn changes the setting approximately 2 PSIG.
3. Set the cut-out pressure with the differential adjustment. Turn the
differential adjustment nut clockwise (in) to increase the pressure or
counter-clockwise (out) to decrease the pressure.
NOTICE
One full turn changes the setting approximately 2 PSIG.
4. Replace the cover, reconnect the power supply and start the unit.
5. Note the pressure gauge reading at which the unit cuts out.
6. Repeat the adjustment procedure if necessary.
The minimum possible differential is approximately 20% of cutout
pressure. It is advisable to have as wide a differential as possible to
avoid frequent starting and stopping of the unit. Note the pressure
gauge reading at which the unit cuts-out and re-establish this point if
necessary.
Note the interaction between the range and differential adjustments,
i.e., if the cut-out is increased, the differential will also increase,
or if the differential is narrowed, the cut-out will be reduced, etc.
These factors must be considered when adjusting the switch and
compensated for accordingly.
22607402 Rev.F
RELEASED 15/Mar/2018 20:10:54 GMT
STARTING UNLOADING SYSTEM
The starting unloading feature exists on certain models. The purpose
of the system is to relieve cylinder pressure when the unit stops,
permitting it to start against a light load. A light load increases the life
of the driver and belts and also reduces the possibility of tripping the
overload relay. The system operates in the following manner:
The centrifugal unloader is attached to the end of the crankshaft as
shown in the following illustrations.
When the unit starts, centrifugal force acts upon the unloader
weights and they swing outward. This permits the plunger and
thrust pin to move inward and the pilot valve to close. The escape
path to atmosphere for the cylinder pressure is now closed and the
compressor pumps air in a normal manner.
When the unit stops, the weights retract, permitting the thrust pin
spring to move the plunger and thrust pin outward. The thrust pin
opens the pilot valve and the trapped air pressure escapes from the
cylinder and intercooler through a passage in the frame end cover,
through the unloader tube and to atmosphere through the inlet
filter/silencer.
Position of weight and thrust pin when unit is operating.
EN-11