Product Overview

VA-4233 Series Electric Valve Actuators Product Bulletin 3
Operation
IMPORTANT: VA-4233 Series Electric Valve
Actuators are intended to
control valves under normal
operating conditions. Where
failure or malfunction of VA-
4233 Series Actuators could
lead to an abnormal operating
condition that could result in
personal injury or damage to
the equipment or other
property, additional devices
(limit or safety controls) or
systems (alarm or supervisory)
intended to warn of, or protect
against, failure or malfunction
of VA-4233 Series Actuators
must be incorporated into and
maintained as part of the
control system.
VA-4233-AGx Series Floating Electric
Valve Actuators
VA-4233-AGx Series Floating Electric Valve Actuators
operate on 24 VAC at 50/60 Hz or 24 VDC, and use a
stepper motor with stall detection circuitry that
operates throughout the entire actuator stroke.
Application of a 24 VAC or VDC control signal between
the Stem Up (white/brown) or Stem Down (brown)
input and the Common terminal will drive the actuator
in the indicated direction. Removal of the signal will
hold the actuator in position. In the event of power
failure, a spring in the actuator automatically returns
the valve to the full stem-up position. Restoration of
power will return the actuator and valve assembly to
normal operation.
VA-4233-BGx Series On/Off Electric Valve
Actuators
VA-4233-BGx Series On/Off Electric Valve Actuators
operate on 24 VAC at 50/60 Hz or 24 VDC, and use a
stepper motor with stall detection circuitry that
operates throughout the entire actuator stroke.
Application of a power signal will extend the actuator,
driving the valve stem down to the end of travel and
holding it in position. Removal of the power signal will
cause a spring in the actuator to automatically return
the valve to the full stem-up position.
VA-4233-GGx Series Proportional Electric
Valve Actuators
VA-4233-GGx Series Proportional Electric Valve
Actuators operate on 24 VAC at 50/60 Hz or 24 VDC,
and use a stepper motor with stall detection circuitry
that operates throughout the entire actuator stroke. All
models employ noise-filtering techniques on the control
signal, in order to eliminate repositioning due to line
noise.
VA-4233-GGx Series Actuators position the valve in
response to a control signal, in a manner defined by
the mode switch that is field selected: 0 to 10, 2 to 10,
or 6 to 9 VDC, or 0 to 20 or 4 to 20 mA input signal. A
built-in direct or reverse (DA/RA) switch allows
selection of the required control action. These
actuators feature an AUTO stroke calibration function
that enables the actuator to scale the selected input
signal and feedback proportionally across the actual
valve stroke. Initial application of a power signal will
drive the actuator and valve assembly to the full
stem-up position and then the full stem-down position,
and will store these positions in nonvolatile memory
(retains data when power is lost or removed). The
actuator will then drive to the position determined by
the applied control signal.
If, during normal operation, the valve stroke increases
due to disk or seat wear, the actuator will automatically
calibrate to the increased stroke range. While AUTO
stroke calibrating, the valve control function could be
lost for up to three minutes. If this temporary loss of
control function will result in system control problems
during start-up, the actuator should be mounted to the
valve and have electric power supplied to it prior to
start-up. Doing so will allow the actuator to AUTO
stroke calibrate itself. The Johnson Controls
M9000-200 Commissioning Tool (ordered separately)
is a convenient method for applying power to the
actuator prior to start-up.
The actuator will AUTO stroke calibrate only once
upon initial power application. Certain conditions, such
as removal of the actuator from the valve, will require
cancellation of the stored memory in order for the
actuator to adjust to its new position once it is
remounted on the valve. Refer to the literature included
with the actuator for step-by-step instructions on how
to cancel the stored memory.