Johnson Controls VA-8051 Specification

The VA-8051 synchronous,
motor-driven actuator provides
floating control of valves with up
to 3/4 in. stroke in heating,
ventilating, and air conditioning
applications. This compact,
non-spring return actuator has a
50 lb. force and is compatible
with a 3-wire, 24 VAC signal.
A 12 VDC signal from a
DSC-8500 may be used with a
VA-8000-104 drive card to
position the VA-8051. A
3400 ohm (nominal) position
feedback potentiometer is also
included for remote position
indication to meters or a
DSC-8500. The VA-8051 can be
ordered factory coupled to
VB Series Valves. See AV-8051
bulletin for code numbers.
Operation
A controller sends 24 VAC to
the up or down terminal on the
circuit board depending on the
desired movement of the valve.
This signal causes the motor to
rotate in the proper direction,
and through the lead screw and
lever, move the valve up or
down. When the controller stops
sending a signal, the valve
remains in place.
When the controller closes the
valve, a shutoff force will build
up. When this force reaches
50 lbs., the lever activates a
force sensor which stops the
motor. Field calibration of the
force sensor is not required. The
actuator maintains the shutoff
force even if power to the
controller is lost. When the
controller signals the valve to
move in the opposite direction,
the shutoff force will be reduced
and the valve will modulate.
© 1988 Johnson Controls, Inc.
Part No.14-548-9 Rev. A
Code No. LIT-977305
VA-8051 Electric Valve Actuator
Floating Control, 50 lb. Force
The internal position feedback
potentiometer is connected to
the R, W, and S terminals.
Specifically, the wiper is
connected to W. The wiper will
be at the R end when the
actuator is retracted and at the
S end when the actuator is fully
stroked.
Product
Control Mode
Supply Voltage
Power Consumption
Feedback
Shutoff Force
Stroke Time
Ambient Operating Temperature
Ambient Storage Temperature
Media Temperature
Accessories
The performance specifications are nominal and conform to acceptable industry standards. For application at conditions
beyond these specifications, consult the local Johnson Controls office. Johnson Controls, Inc. shall not be liable for
damages resulting from misapplication or misuse of its products.
Valve and Actuator Manual 977
Actuators and Positioners Section
Fig. 1: VA-8051-1 Connected to VB-3754

Specifications

VA-8051-1 Electric Valve Actuator
Floating Control, 3-W ire
24 VAC + 6 V, -4V, 200 mA, 50/60 Hz
6 VA
3400 Ohms 25%, 20 VDC Max Input Voltage
50 lb. Force Minimum
1/2 in. Stroke: Approx. 65 Sec
3/4 in. Stroke: Approx. 90 Sec
0 to 140 F (-18 to 60 C), 90% RH Max,
85 F Max Dew Point
-40 to 150 F (-40 to 65 C)
Water: 190 F (88 C)
Steam (with Insulator Kit): 280 F (138 C)
VA-8000-101 Steam Insulator Kit
VA-8000-102 Valve Position Indicator Kit
VA-8000-104 Auxiliary Interface Board
Product Bulletin VA-8051
Issue Date 0988
1