Daikin DBG Series, Общее руководство пользователя

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and calculate if an unbalanced condition exists between phases.
Calculate percent voltage unbalance as follows:
Three Phase Models
3) PERCENT VOLTAGE
UNBALANCE
2) MAXIMUM VOLTAGE DEVIATIONS
FROM AVERAGE VOLTAGE
1) AVERAGE VOLTAGE
HOW TO USE THE FORMULA:
EXAMPLE: With voltage of 220, 216, and 213
1) Average Voltage = 220+216+213=649 / 3 = 216
2) Maximum Voltage Deviations from Average Voltage = 220 - 216 = 4
3) Percent Voltage Unbalance = 100 x = = 1.8%
Percent voltage unbalance MUST NOT exceed 2%
.
4
216
400
216
= 100 X
Control Voltage Check
Close the disconnect switch to energize control transformer. Check
primary and secondary (24V) of control transformer.
AIR FLOW ADJUSTMENTS
Refer to the following “Motor Sheave Adjustments” section.
When the final adjustments are complete, the current draw of the
motor should be checked and compared to the full load current
rating of the motor. The amperage must not exceed the service
factor stamped on the motor nameplate. The total airflow must
not be less than that required for operation of the electric heaters
or the furnace.
If an economizer is installed, check the unit operating balance with
the economizer at full outside air and at minimum outside air.
NOTE: Airflow setting below 300 CFM/Ton is not recommended, as
evaporator freezing or poor unit performance is possible.
For 2-speed models, airflow adjustments must be made with the
evaporator motor operating at high speed (in 2nd stage cooling or
in heat mode). 2-speed models have a “V” OR “W” in the 8TH digit
of the model number (e.g. DBG3003
V
).
Evaporator Fan Rotation Check
Check that fan rotates clockwise when viewed from the drive side
of unit and in accordance with rotation arrow shown on blower
housing. If it does not, reverse any two incoming power cables at
Single Point Power Block. In this case, repeat bearing check.
Do not attempt to change load side wiring. Internal wiring assures
all motors and compressors will rotate in correct direction once
evaporator fan motor rotation check has been made.
Electrical Input Check
Make preliminary check of evaporator fan ampere draw and verify
that motor nameplate amps are not exceeded. A final check of amp
draw should be made upon completion of air balancing of the duct
system (see Appendix B).
Set Evaporator Fan Rpm
Actual RPM’s must be set and verified with a tachometer or strobe
light. Refer to Appendices A and B for basic unit fan RPM. Refer
also to “Airflow” section of this manual. With disconnect switch
open, disconnect thermostat wires from terminals Y and W. This
will prevent heating and mechanical cooling from coming on. Place
a jumper wire across terminals R and G at TB1 terminal block. Close
disconnect switch; evaporator fan motor will operate so RPM can
be checked.
For gas heat units, the airflow must be adjusted so that the air
temperature rise falls within the ranges given stated on Data Plate
(see Appendix A - Blower Performance).
The drive on the supply fan is typically set in the middle of the RPM
range. The drive motor sheave pitch diameter is field adjustable for
the required airflow. Refer to “Motor Sheave Adjustments” section.
Upon completion of the air flow balancing, we recommend re-
placing the variable pitched motor sheave with a properly-sized
fixed sheave. A matching fixed sheave will provide longer belt and
bearing life and vibration free operation. Initially, it is best to have a
variable pitched motor sheave for the purpose of airflow balancing,
but once the balance has been achieved, fixed sheaves maintain
alignment and minimize vibration more effectively.
Bearing Check
Prior to energizing any fans, check and make sure that all setscrews
are tight so that bearings are properly secured to shafts.
Tension and Alignment Adjustment
Correct belt tension is very important to the life of your belt. Too
loose a belt will shorten its life; too tight, premature motor and
bearing failure will occur. Check you belt drive for adequate “run-
in” belt tension by measuring the force required to deflect the
belt at the midpoint of the span length. Belt tension force can be
measured using a belt tension gauge, available through most belt
drive manufacturers.
SPAN LENGTH t
*DEFLECTION
FORCE
h
C
d H
D
* Apply force to the center of the span.
t = Span length, inches
C = Center distance, inches
D = Larger sheave diameter, inches
d = Smaller sheave diameter, inches
h = Deflection height, inches
DRIVE BELT TENSION ADJUSTMENT