Valve Actuators Features and highlights
; Quick and easy installation.
; No separate linkage required.
; 1-1/2 in. (38 mm) stroke on
; No adjustments required.
; Accurate valve positioning.
; Low power consumption.
; Selectable 0(2) to 10 Vdc or 0(4) to 20
mA input signal with L721B1008.
; Position feedback with L721B1008.
; High close-off ratings.
; Direct/reverse acting with L721B1008.
; Force-limiting end switches.
; Manual operator. APPLICATION
; Synchronous motor. The L721B1008 Non-Spring Return Electric Linear
Valve Actuators are modulating control actuators ; Corrosion-resistant design. used with controls that provide an analog output of
0 to 10 Vdc or 2 to 10 Vdc. These actuators ; Maintenance free.
operate standard Alerton globe valves in HVAC ; Conduit connector knockout. applications. An internal selector plug can be
used to reverse the direction of action.
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Weight: 5.1 lb (2.3 kg).
Power Input: 24 Vac (+10%, -15%), 60 Hz. Power Consumption: 11 VA maximum at 24 Vac.
0 to 10 Vdc or 2 to 10 Vdc.
Cover: ABS plastic.
Yoke and Base: Diecast aluminum.
Stem Force: 405 lbf (1800N).
Two knockout holes for 1/2 in. conduit standard on actuator case. Ambient Ratings: Fig. 1: Approximate dimension of L721B1008 Temperature: Actuator
Ambient Range: 14?F to 122?F (-10?C to +50?C).
Storage Range: -40?F to +158?F (-40?C to +70?C). Ordering Information Humidity Range: 5 to 95 percent relative humidity, noncondensing. Item Description Number Approvals: Canadian Standards Association Listed. L721B1008 Non-Spring Return Electric Underwriter.s Laboratories, Inc. UL94-5V Flame Linear Valve Actuators
Retardant (file E181716). Meets CE
Protection Standard: IP54. Accessories: ; 43191680-102 Dual Auxiliary Switch (for 24 Vac use only). ; 43196000-001 High Temperature Kit (for actuators with 3/4 in. stroke). Increases maximum temperature to 428?F (220?C). ; 43196000-102 High Temperature Kit (for actuators with 1-1/2 in. stroke). Increases
maximum temperature to 428?F (220?C).
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When Installing this Product. 1. Read instructions carefully. Failure to follow them 1. Release the stem button retaining clip to secure could damage the product or cause a hazardous the stem button. Check to make certain the stem condition. button is secured by the retaining clip. 2. Check ratings and description given in the 2. Pull off the manual operation knob. specifications to make sure the product is suitable for 3. Remove the cover from the actuator using a your application. Phillips or crosspoint screwdriver. See Fig. 3. 3. Installer must be a trained, experienced service technician.
4. After installation is complete, check out product operation as provided in these instructions.
Electrical Shock or Equipment Damage Hazard. Can shock individuals or short equipment
Disconnect power supply before installation.
Install the actuator in a location that allows enough clearance
for mounting accessories and for servicing.
Equipment Damage Hazard.
Can damage actuator due to condensation or a valve gland leak.
Install the actuator in a position above horizontal.
1. Place the actuator on the valve with the U-bolt around
the valve collar. See Fig. 2.
When tightening the set screws, first tighten the right set screw. See Fig. 2.
2. Place the U-bolt against the valve collar and secure
the actuator to the valve by turning each U-bolt nut
3. NOTE: To assure even pressure on the collar, first
tighten the nuts finger-tight and then alternate turning each U-bolt nut until both are snug.
4. Push aside the stem button retaining clip and hold. See Fig. 2.
5. Lift the valve stem until the head of the valve stem button is inside the large slot of the stem button retaining clip on the actuator.
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Electrical Shock or Equipment Damage Hazard.
Can shock individuals or short equipment
Disconnect power supply before installation.
1. All wiring must comply with local electrical codes,
ordinances and regulations.
2. Voltage and frequency of the transformer used with the
actuator must correspond with the characteristics of the power supply and those of the actuator. Fig. 5: Typical L721B1008 wiring diagram
NOTE: See Fig. 5 for typical wiring hookups.
1. Feed power and control wires through the conduit
connector located on the bottom of the actuator case.
Equipment Damage Hazard.
Conduit connection or removal can break an
When removing or attaching conduit, use a wrench to
support the motor connector.
2. Using the appropriate wiring diagram (see Fig. 5),
connect power and control wires to the actuator.
Make sure that all wiring is correct.
3. For the L721B1008 only: Check selector plugs for
proper settings. See Signal Input Failure section for
details. 4. When wiring is complete, replace the actuator cover Fig. 6: Replacing actuator cover and control knob (see Fig. 6). 5. Apply power and control signals to the actuator. Auxiliary Potentiometers The 43191679 Auxiliary Potentiometers can be used
as feed-back potentiometers and to provide remote
indication of the valve position. See the Accessories
section for part numbers.
See Installation Instructions packed with the
potentiometers for details.
The 43191680 Dual Auxiliary Switch can be used on
both the L721B1008 Electric Linear Valve Actuators.
Switching points are adjustable over the full actuator
stroke. For example, the switch can be used to switch
pumps or to provide remote indication of any stroke
position. See the Installation Instructions packed with the auxiliary switch for details.
IMPORTANT Use the 43191680 Dual Auxiliary Switch only with th6670 185 Avenue Northeast, Redmond, WA 98052 USA. Tel: 425.869.8400. Fax: 425.869.8445. www.alerton.com 4 of 6 Rev.001
24 Vac applications.
General L721B1008 The drive of the actuator synchronous motor is converted into the linear motion of the actuator stem by using a worm Signal Input Failure gear transmission. A button retainer clip connects the
actuator stem to the valve stem. Using selector plug W1, the actuator can be set to run
to one of three positions in event of a signal failure:
; 0%: Actuator position corresponds with 0 or 2 Vdc signal. The internal force sensor, using installed microswitches, ; 50%: Actuator stem in mid-position. turns off the actuator when the specified stem force is ; 100%: Actuator position according to 10 Vdc signal. reached. NOTE: If W4 is set to the mA position, the actuator
always runs to 0 percent. Manual Operation The L721B1008 is equipped with a manual operator knob
Output Signal Feedback (F) (see Fig. 7) to open or close the valve in the event of
power failure: An analog output signal (2 to 10 Vdc) that represents 1. Turn off or disconnect the power supply before the actual actuator stem position is available at manually operating the actuator. terminal F. It can be used for remote indication of the 2. Push down on the manual operator knob and turn the stem position.
knob: a. Counterclockwise to drive the stem downward. With the actuator stem fully down, the output signal is b. Clockwise to draw the stem upward. 10 Vdc. The output of the signal does not change when the actuator action reverses using W3 or W4 IMPORTANT (see Signal Input Failure section and Fig. 8). Manual operation allows very high closing force that can jam the actuator spindle, exceed the force switch ratings, and stop the motor. After a manual valve close-off operation, release the spindle one turn by turning the manual operator knob. This will ensure automatic disengagement of the manual operator upon power resumption.
NOTE: If the manual operator knob is not pushed in while turned, it will rotate only a short distance before disengaging without power resumption.
Fig. 8: Location of selector plugs
Fig. 7: Manual operator knob
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Actuator Override To override the control signal (for freeze protection or similar applications), connect the 24 Vac common (T2) to either terminal O1 or O2. Connecting to terminal O1 fully extends the actuator stem. Connecting to O2 fully retracts the actuator stem.
The control signal (+) is ignored when the override signal is applied to terminal O1 or O2. This override can be achieved with a switch or a relay. See Fig. 9.
Direction of Action
The direction of action can be changed by repositioning the selector plug W3.
CHECKOUT The actuator can be checked out either directly or using a Fig. 9: Connections for overriding control signal to controller. drive actuator to a specific position.
1. Mount the actuator for the required application. Controller Checkout 2. Check the valve position and make sure that 24 Vac 1. Adjust the setpoint of the controller to call for is correctly applied to the actuator. opening or closing the valve. Observe the actuator. 3. Apply the control signal to the appropriate leadwires 2. If the valve is closed, it should begin to open. to move the valve in the required direction. 3. If the valve remains closed, move the setpoint 4. If the actuator does not move, make sure the actuator further toward the open setting. is properly installed. 4. If the valve does not move, check for 24 Vac in the 5. If the actuator is correctly installed and does not run, actuator power input. replace the actuator. 5. If 24 Vac is present and the actuator does not
operate, reverse the controller leadwires to determine if the device is incorrectly wired. 6. If wiring is correct, 24 Vac is present on the power
input terminals, and the actuator does not run, replace the actuator.
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