Reznor R6GN Option - Installation - High Static Blower Drive - Light Commercial - Manual (Page 9)

9
Example:
AB = 451V
BC = 460V
AC = 453V
2. Determine the average voltage in the power supply.
3. Determine the maximum deviation:
4. Determine percent of voltage
imbalance by using the results
from steps 2 & 3 in the following
equation.
max voltage deviation
from average voltage
= 100 x
average voltage
% Voltage Imbalance
6
454
100 x = 1.32%
Example:
1. Measure the line voltages of
your 3-phase power supply
where it enters the building
and at a location that will
only be dedicated to the unit
installation. (at the units circuit
protection or disconnect).
Unbalanced 3-Phase Supply Voltage
Voltage unbalance occurs when the voltages of all phases of
a 3-phase power supply are no longer equal. This unbalance
reduces motor effi ciency and performance. Some underlying
causes of voltage unbalance may include: Lack of symmetry in
transmission lines, large single-phase loads, and unbalanced
or overloaded transformers. A motor should never be operated
with a phase imbalance (in supply) that is greater than 2%.
Perform the following steps to determine the percentage of
voltage imbalance:
In this example, the measured line voltages were 451,
460, and 453. The average would be 454 volts (451 +
460 + 453 = 1,364 / 3 = 454).
The amount of phase imbalance (1.32%) is satisfactory since
the amount is lower than the maximum allowable 2%. Please
contact your local electric utility company if your voltage
imbalance is more than 2%.
Example:
From the values given in step 1, the BC voltage (460V)
is the greatest difference in value from the average:
Highest Value 460 - 454 = 6
454 - 451 = 3
454 - 453 = 1
Blower Speed
The blower speed for these accessory kits is not set at the
factory and must be verifi ed for each installation. For optimum
system performance and comfort, refer to blower performance
data (Tables 7 - 28, pages 11 - 32) for proper operating range.
Always verify drive belt are secure and tensioned properly.
Also inspect variable pitch sheaves for proper tightness of
the set screws.
Measuring the Blower Speed
For units equipped with either an electric heat kit or gas heat
exchanger, the best method to determine the delivered CFM
is through a temperature rise measurement. Using quality
instruments, insert a temperature probe into the units supply
and return ducts. Provide the unit a call for the maximum heat
capability and either calculate the airfl ow for the measured
temperature rise or reference Tables 29 or 30 (page 33) to
estimate the CFM.
NOTE: For high static situations, never operate the blower
with the access panels removed for any length of time as
the blower motor may over-amp and trip the internal/external
protection. If it is desired to verify the blower RPM, always use
a remote indicator with the access panels closed.
To verify the blower rotation, the contactor can be manually
actuated for a brief period to “bump” the motor or the G terminal
can be briefl y energized from R.
If necessary adjust the motor sheave to optimize the air
delivery. Always verify the motor amp draw at the contactor
to ensure it is less than the SFA for the unit/motor voltages
at the selected sheave setting
CAUTION:
To avoid personal injury or property damage, make
certain that the motor leads do not make contact
with any uninsulated metal components of the unit.
Changing the blower speed:
1. Disconnect all electrical power to the unit and remove the
blower access panel.
2. Loosen the motor tension bars to allow removal of the blower
belt from the motor sheave.
3. Loosen top set screw on motor sheave and turn clockwise
to close (increases blower speed), or counterclockwise to
open (decreases blower speed). NOTE: Make sure the center
of the sheave and pulley are properly aligned. Adjust the
sheave and pulley’s position on the motor or blower shaft
if necessary.
4. Replace belt on pulleys and position motor mounting plate
to correct position for proper belt tension.
5. Tighten tension bar bolts or adjustable motor base.
External Motor Overload
If installed, Verify that the overload is properly set for the motor
SFA and that it will trip when manually tested.