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Technical Instructions
Document No. 155-177P25
December 15, 2004
Sizing
Mounting and
Installation
Page 8
The number of actuators required depends on several factors. To determine the
quantity of actuators required for the installation:
1. Obtain damper torque ratings (ft-lb/ft
2. Determine the area of the damper.
3. Calculate the total torque required to move the damper:
Total Torque = Torque Rating × Damper Area
4. Select the total quantity of actuators required:
Number of actuators =
1
Safety Factor: When calculating the number of actuators required, a safety factor
should be included for unaccountable variables such as slight misalignments, aging of
the damper, etc. A suggested safety factor is 0.80 (or 80% of the rated torque).
Mechanical coupling of the actuator is allowed if:
1. The same type of actuator is used.
2. The power trunk can handle added components.
3. The same power and control inputs go to both actuators (parallel wiring).
Figure 13. Acceptable NEMA 2 positions.
•
The actuator must be placed on the damper shaft so that the front of the actuator is
accessible. The label and the manual override button are the front side.
•
The minimum damper drive shaft length is 3/4-inch (20 mm). The shaft length
determines whether the shaft adapter will be mounted on the front or back side of
the actuator.
•
See Specifications for minimum and maximum damper shaft dimensions.
•
Mount the position indicator to show either the clockwise or counterclockwise 0 to
90 scale.
•
A mounting bracket is included with the actuator.
-
Detailed mounting instructions are included with each actuator.
-
The shaft adapter and mounting parts are shipped in a separate container with
the actuator.
•
The actuator is shipped from the factory with a 5° pre-load to ensure tight close off
of the damper.
OpenAir
2
or Nm/m
Total
Damper
1
SF
x Actua
tor
Torque
NEMA 2
TM
NSR Rotary Electric Damper Actuator
24 Vac 3-position Control
2
) from the damper manufacturer.
Torque
required
(Refer
to
Specificat
Siemens Building Technologies, Inc.
ions)
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