Hoffman Controls 865-3AA Series Recalibration Instructions

Hoffman
Recalibration Instructions

General

The 865-3AA Series Three Phase Condenser Motor Speed
Controller is factory calibrated and should not require
recalibration. Recalibration is not recommended until the
Controller is installed and the factory calibration perfor-
mance is observed to be unacceptable.
The Controller is designed to allow full speed for all
ambient temperatures until a liquid line temperature of 80°F
is obtained (≈ 60°F ambient). Between 80°F and 50°F liquid
line temperature, the Controller will modulate the condenser
fan motor(s) speed until the ambient temperature results in
a liquid line temperature of 50°F (≈ 25°F ambient). At 50°F,
the Controller will be operating at the preset minimum RPM.
Liquid line temperatures below 50°F will disconnect the
condenser fan motor from the line. Condensor motor will
cycle OFF and ON, over time, from 50ºF to 53ºF at Minimum
Speed until ambient precludes liquid line Temperatures
above 50ºF to occur.
Controllers should not be re-calibrated to condensing
pressure. The condensing pressure, once minimum speed is
reached at 50°F-liquid line (≈ 25°F ambient), should provide
100-psi (R22 for TX valve) plus the specific evaporator pres-
sure for the application/refrigerant. When the Controller is
unable to provide this minimum pressure limit, recalibration
may be required.
Proper operating performance can only be obtained with a
saturated, sub-cooled liquid at the Sensor at all times.
Verification of proper super heat control at TX valve
is important (6–10ºF ≈ super heat). Improper super heat
control may cause or allow excessive liquid flooding or
abnormally low evaporator pressure. Either could adversely
effect head pressure control performance.
The following instructions are provided for liquid line
sensing (preferred method), mA/volts DC inputs, or manual
speed control.
Field Calibration for
Thermistor Sensor
1. Disconnect Thermistor Sensor.
2. Adjust the CALIBRATE pot fully counter-clockwise (CCW).
3. Place the calibration jumper (J1) tab to the CAL/MAN
SPD position to enable the on-board sensor simulator.
4. Set both the MAX. and MIN. adjustment pots to mid
range.
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Controls
Three Phase Head Pressure Controller
5. Adjust the CALIBRATE pot clockwise (CW) until the
FULL L.E.D. light comes ON. Backoff the CALIBRATE pot
until the FULL L.E.D. light just goes OFF. This places the
calibration point at the top end of the modulation range.
6. Adjust the MAX. ADJ. pot to achieve the desired max
speed for the top end of the modulating range.
7. Adjust the CALIBRATE pot counter-clockwise (CCW)
until the OFF L.E.D. light comes ON (this will shut
the motor OFF). Now, slowly adjust the CALIBRATE
pot clockwise (CW) until the OFF light goes OFF (the
modulate L.E.D. will come ON at this same time).
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Allow the soft-start time to expire
(10 seconds).
8. Adjust the MIN. ADJ. pot to achieve the desired min
speed at the bottom end of the modulating range. Do
not adjust below 200 RPM minimum.
9. The Minimum Adjustment pot interacts with the
Maximum Adjustment pot; therefore repeat steps 5
through 8 one time.
10 Remove the jumper tab J1 from the CAL/MAN SPEED
position and return it to its OPERATE/STORE position.
11. Adjust the CALIBRATE pot fully counter-clockwise (CCW).
12. Reconnect the Thermistor Sensor.
This recalibration procedure allows adjustment of the
min/max fan speeds within the modulation range,
but will not change the span or fan cutoff threshold
(temperature) of the Controller.
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865-3AA Series
CAUTION
NOTE
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