Specifications

Technical Instructions OpenAir GMA Series, Spring Return, 62 lb-in Rotary, Electronic Damper Actuators
Document Number 155-315P25
January 26, 2011
Page 8 Siemens Industry, Inc.
Operation,
continued
GMA13x
A floating control signal controls the damper actuator. The actuator’s angle of
rotation is proportional to the length of time the signal is applied. A 24 Vac/dc
control signal to wire 6 (Y1) causes the actuator coupling to rotate clockwise. A 24
Vac/dc control signal to wire 7 (Y2) causes the actuator coupling to rotate
counterclockwise.
With no control voltage, the damper actuator holds its position. In the event of a
power failure, the actuator spring returns to the "0" position.
Overload Protection
In the event of a blockage in the damper, the actuator is overload protected over
the full range to prevent damage to the actuator.
Life Expectancy
An improperly tuned loop will cause excessive repositioning that will shorten the life
of the actuator.
Sizing
The type of actuator required depends on several factors:
1. Obtain damper torque ratings (lb-in/ft
2
or Nm/m
2
) from the damper
manufacturer.
2. Determine the area of the damper.
3. Calculate the total torque required to move the damper:
Total Torque =
SF
AreaDamper Rating Torque
1
×
4. Select a spring return actuator using Table 2.
1
Safety Factor: When calculating the total torque 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.
NOTE: Mechanically coupled actuators must be of the exact same type except
for the dual auxiliary switches and feedback potentiometer options. Use
the correct mounting bracket. See
Table 2.
Table 2.
DC Power (24 Vdc) AC Power (24 Vac, 120 Vac)
Total Torque Actuator Total Torque Actuator
<62 lb-in (7 Nm)
GMA1xx
<62 lb-in (7 Nm)
GMA
>62 lb-in <160 lb-in
(>7 Nm <18 Nm)
GCA12x, GCA13x, GCA15x*
>62 lb-in
<160 lb-in
(>7 Nm <18 Nm)
GCA
>160 lb-in <320 lb-in
(>18 Nm <36 Nm)
Use tandem mounting bracket
ASK73.1 with any combination
of:
• GCA12x actuators
• GCA13x actuators
Use tandem mounting bracket
ASK73.2U with any
combination of GCA151 and
GCA156 actuators.*
>160 lb-in
<320 lb-in
(>18 Nm <36 Nm)
Use tandem mounting bracket ASK73.1
with any combination of:
• GCA12x actuators
• GCA22x actuators
• GCA13x actuators
• Use tandem mounting bracket
ASK73.2U with any combination of:
• GCA151 and GCA156 actuators*
• GCA161 and GCA166 actuators