Hoffman Controls 865D Series Installation And Operating Instructions Manual

Hoffman | Controls
Installation & Operating
Instructions
CAUTION
Failure to read and understand the accompanying
instructions and diagrams or failure to complete
the "Checkout Procedure" prior to energizing the
Control may result in permanent damage to the
Control.
General
The 865D Low Ambient Three (3) Phase Head Pressure Control
is designed to modulate three phase condenser fan Motors in air
conditioning and refrigration systems. The control monitors the head
pressure by sensing 1) the sub-cooled liquid line temperature, or 2)
via a 0-10 VDC or 4-20 mA control signal indicating the system's
pressure. The controller varys the air volume through the condenser
thus regulating head pressure for proper heat rejection in low ambient
conditions.
The 865D Series installation instructions are limited to three
phase, direct connected, propeller type, condenser fan motor appli-
cations. These applications require continuously variable speed
High Slip tolerant/Ventilated (HS/V), 850/1150 RPM, direct drive,
vertical shaft designed motors approved by the motor manufacturer
for continuous variable speed operation.
The installation, start-up and servicing of the 865D Control
and the continuously variable speed motor can be hazardous due
to the technical scope and magnitude of the electrical/mechan-
ical components encountered.
A qualified technician with knowledge and experience in
controls and refrigeration will be required. All safety precautions,
instructions, labels, and tags on the items being installed as well as
those of the equipment manufacturer should be observed.
The 865D is offered with a NEMA 3R rainproof enclosure for
field installation in the weather/ambient.
Applications
The 865D Control typically modulates continuously variable
speed HS/V (High Slip/Ventillated) three (3) phase condenser fan
motor(s). Two identical condenser motors, of same manufacturer,
type, model, RPM and identical propeller fans, may be controlled
by one 865D Control. In either case, the 8 amp, per phase, rating of
the 865D Control must not be exceeded.
A properly applied 865D Control may be used to extend the
operating range of A/C or refrigeration systems, permitting opera-
tion at lower outdoor ambient temperatures. When more than a
single liquid line sensor requires monitoring, use the HCC 851-
MS series Multiple Sensor Selector.
The 865D Control can also be used as a Manual three (3) phase
3 Phase Head Pressure Controllers
Applications Con't
Fan Speed Control by using the MIN SPD potentiometer or by a
0-10Vdc or 4-20mA signal
The 865D can either be factory or field calibrated to optimize the
throttling range of the continuously variable speed HS/V motor(s)
for air-cooled condenser applications.
Controller/Motor Operation
Recalibration of the 865D's factory calibrated settings
can be acomplished in the field when required. If reca-
libration is required, see settings.
The Controller is designed to maintain synchronous (full) speed
for all liquid line temperatures above 80°F. At 80°F liquid tempera-
ture, (60°F ≈ ambients) the Controller initiates phase proportioning
by reducing motor speed to approximately 1000 RPM. Speed reduc-
tion continues as liquid temperature decreases down to a minimum
speed which occurs at 50°F (25°F ≈ ambient).
Further reduction in liquid line sub-cooling will remove (discon-
nect) the motor from the line and the motor will cycle "Off". The
motor will restart at 53ºF, 3ºF differential at approximately 100
RPM above where the motor cycled OFF, and modulates back to
the Minimum speed. OFF time will increase as Ambients continue
to fall until liquid line temperature remains below 50ºF. This feature
also allows the 865D to be "Off" at start-up when the ambient and
liquid line are below 50°F. Conversely, the 865D controls the motor
speed functions in reverse as previously described as temperatures
increase.
A 0-–10VDC or 4–-20mA optional signal input is available.
These inputs may be used when pressure transducers or other analog
outputs are preferred.
Below is the general sequence of events required to set up the
865D Control for operation:
Operational Overview
The 865D Control is factory calibrated for use with the supplied
liquid line temperature sensor and is set for 50ºF to 80ºF operation
with a minimum speed of 300RPM. These setting can be changed
as required.
A 0-–10VDC or 4–-20mA optional signal input is available.
These inputs may be used when pressure transducers or other analog
outputs are preferred.
A) Use the MODE JP1 jumper to select either Head Pressure
Control operation or Motor Speed control operation.
B) The 865D Control will automatically sense the type of
input signal being used.
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865D Series