Johnson Controls VA-8051 Manuale utente

Valve and Actuator Manual 977

Actuators and Positioners Section

Product Bulletin VA-8051

Issue Date 0988

Part No.14-548-9 Rev. A

Code No. LIT-977305

VA-8051 Electric Valve Actuator

Floating Control, 50 lb. Force

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.

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.

Specifications

Product VA-8051-1 Electric Valve Actuator

Control Mode Floating Control, 3-Wire

Supply Voltage 24 VAC + 6 V, -4V, 200 mA, 50/60 Hz

Power Consumption 6 VA

Feedback 3400 Ohms ±25%, 20 VDC Max Input Voltage

Shutoff Force 50 lb. Force Minimum

Stroke Time 1/2 in. Stroke: Approx. 65 Sec

3/4 in. Stroke: Approx. 90 Sec

Ambient Operating Temperature 0 to 140°F (-18 to 60°C), 90% RH Max,

85°F Max Dew Point

Ambient Storage Temperature -40 to 150°F (-40 to 65°C)

Media Temperature Water: 190°F (88°C)

Steam (with Insulator Kit): 280 °F (138°C)

VA-8000-101 Steam Insulator Kit

Accessories VA-8000-102 Valve Position Indicator Kit

VA-8000-104 Auxiliary Interface Board

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.

Fig. 1: VA-8051-1 Connected to VB-3754

2VA-8051 Product Bulletin

Wiring

All wiring must be in accordance

with applicable electrical code

requirements. Input lines to the

actuator must be wired correctly

for the valve to move in the

proper direction.

VA-8051 Product Bulletin 3

Wiring is to a terminal strip

labeled DWN (Down), COM

(Common) and UP,

respectively. Wiring is to the

terminals labeled R (Retracted

end), W (Wiper), and S (Stroked

end) for the feedback

potentiometer.

(See Fig. 6).

Retrofit Installation

!CAUTION:Do not use on

valves having a stroke over

3/4 in. Actuator travel over

3/4 in. will damage the

actuator.

!WARNING:Equipment

Damage Hazard. Do not

drive the VA-8051 actuator

unless it is mounted to a

valve. This can result in

permanent damage to the

actuator.

1. Remove the V-3000

actuator, upper spring plate

and spring. (See Fig. 2).

a. Disconnect the air line

to the actuator.

b. Remove the actuator

by loosening the

actuator set screw on

the bottom of the lower

diaphragm case. Lift

the actuator off of the

valve.

c. Hold the stem

extension firmly with a

9/16 in. box-head

wrench and with a

small screwdriver,

loosen the stem locking

screw.

d. For V-3000 valves,

compress the spring

using the X-200-8058

spring compression

tool. For V-3800

valves, compress the

spring with hand

pressure.

e. Using a 9/16 in. box-

head wrench, unscrew

the stem extension. Lift

the spring and upper

spring plate off the

valve. Remove the

spring compression

tool if used.

f. Thread the lower spring

plate up the

centerpiece stuffing box

to increase spacing

between the spring

plate and the flat valve

yoke mounting surface.

2. Unpack the actuator and

make sure the lever plate is

within 1/4 in. of the upper

stop.

3. Install the valve packing

that is provided according

to the instructions included

with the parts.

4. Thread the 1/4 in. Palnut,

open side down, onto the

valve stem and all the way

to the end of the threads.

5. Loosely install the actuator

by sliding the actuator yoke

between the spring plate

and the yoke surface.

Finger tighten the plate to

hold the actuator in place.

(See Fig. 3).

6. Obtain a source of 24 volt

AC power. Wire a switch to

allow control of the 24 volts

AC to the DWN and COM

terminals of the actuator.

7. Thread the coupler onto the

valve stem while applying

24 volts AC as necessary.

The coupler should thread

down the stem until

approximately 1/8 in. of

thread remains between the

coupler and the Palnut.

Fig. 2: Exposed V-3000 Actuator

4VA-8051 Product Bulletin

8. Reverse the actuator and

drive it up until it stops on

the limit switch. Check to

make sure the gap between

the lever plate and the

molded upper stop is

1/16 in. (.047 to .093 in.).

Set with flat washer gage

supplied. (See Fig. 5).

Repeat steps 6, 7 and 8

until the gap falls into this

range when the actuator

stops.

9. With the valve driven fully

up to hold tension on the

stem and coupler, thread

the Palnut up the stem until

it contacts the coupler.

Tighten Palnut to coupler

with 1/2 in. and 7/16 in.

wrenches.

10. Secure the actuator in place

by tightening the spring

plate with a large

screwdriver.(See Fig. 3).

11. Drive the actuator fully up

and down at least three

complete cycles before

again checking that the

lever and its drive coupler

stop before contacting the

upper stop and the lower

end of the yoke casting.

!CAUTION:Use

VA-8000-101 Insulator Kit

for steam applications

280°F (138°C) Maximum.

VA-8051 Product Bulletin 5

Repair Information

Field repairs must not be made.

For a replacement VA-8051,

contact the nearest Johnson

Controls branch office.

Application and Drawing

Identification

Fig. 3: Isometric Drawing

Fig. 4: VA-8051-1 Dimensions in./mm.

Fig. 5: Internal View

6VA-8051 Product Bulletin

Fig. 6: DSC-8500 Application Wiring

(Incremental Control with Position Indication or Proportional Control)

Controls Group

507 E. Michigan Street

P.O. Box 423 Printed in U.S.A.

Milwaukee, WI 53202

Indice

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