Troubleshooting guide

33
· Oil Separator Heater Temperature – This con-
trol limit determines when the oil separator
heater is energized. A decrease in oil separator
temperature below the ONsetpoint energizes the
oil separator heater. On an increase in oil sepa-
rator temperature above the OFF setpoint, the
oil heater is de-energized.
· Oil Pump Restart – To determine the ON and
OFF values for the pressure ratios, take the ab-
solute discharge pressure (PSIA), and divide it
by the absolute suction pressure (PSIA). If the
pressure ratio is below the ON setpoint value,
the oil pump will restart and stay on until the
pressure ratio increases above the OFF setpoint.
This enables a high stage compressor with a part
time oil pump to temporarily operate under con-
ditions requiring a full time oil pump.
EXAMPLE: To calculate the OFF value, if
the absolute discharge pressure is 200 PSIA and
the desired absolute suction pressure of the cut-
out point is 67 PSIA, the discharge pressure is
divided by the suction pressure. The result is a
OFF value of approximately 3.0. This would
then be entered for the OFF pressure. Now
determine the ON value, take the absolute dis-
charge pressure (200 PSIA) and divide this by
the desired absolute suction pressure (71 PSIA).
This results in a ON valve of 2.8.
· Capacity Slide Adjustment Range – This con-
trol limit determines the capacity range the Ca-
pacity Slide Adjustment factor will be active.
The factor will be active from 0% capacity and
will be deactivated when the OFFsetpoint is
reached. On a decrease in capacity below the
ON set point, the factor will be active.
· Minimum Run Capacity – The Minimum Run
Capacity is the minimum capacity the compres-
sor will be allowed to run at. When the com-
pressor is started, it will be loaded to the Mini-
mum Run Capacity control setpoint minus 5%.
This is done to prevent the capacity control from
hunting if the load is not great enough to keep
the compressor capacity at the Minimum Run
Capacity setpoint. On a call for unloading, the
compressor will unload until it reaches the Mini-
mum Run Capacity control setpoint. It will re-
main there until the suction pressure reduces and
the compressor cycles off on the Suction Pres-
sure On/Off control setpoint.
Volume Slide Adjustment Factor – This value is
normally zero (0) and will not require changing.
However, if the system operating conditions show
the volume ratio is not at the optimum value for
the system, this value can be adjusted up or down
to permit the most efficient positioning of the vol-
ume slide valves. To determine the value to enter,
first ensure that the system is in a steady operating
state and place the volume side in manual. NOTE:
The volume position setting and increase the vol-
ume side position slowly until the lowest amper-
age level is achieved. If the amperage level rises
instead of falls, decrease the volume slide posi-
tion until the lowest amperage is achieved. Record
the differential from the original position. This will
then be adjustment factor to enter for our system.
NOTE: Negative numbers can be used for this
setting. This setpoint is active on a drop in capac-
ity below the Capacity Slide Adjustment Range
cut-in (ON) setting. The adjustment is disabled
when capacity rises above the Adjustment Range
OFF setting. Normally, the “ON-Off” set points
should both be set at 100%, so the volume side
adjustment factor will be applied over the full range
of 0 to 100%
· Economizer Solenoid – This control limit deter-
mines when the economizer solenoid is energized.
When the percentage of compressor capacity re-
duces below the Economizer Solenoid OFFset
point, the solenoid is energized.
· Current Transformer Ratio – The value entered
must agree with the Current Transformer Ratio
on the current transformer being used. The cur-
rent transformer is mounted in the compressor mo-
tor conduit box. The ratio is stated as the ratio of
measured current to a nominal full scale current
in the secondary of 5 amps; only the first of these
is entered. For example, if the ratio reads 250/5,
enter 250.
Compressor Control