ML6874
Valve Actuator
PRODUCT DATA
FEATURES
• Allows the use of one common transformer
power supply for multiple actuators and
controllers
• Self-contained, motorized valve linkage
• Linkage self-adjusts to valve stroke of up to
19mm (3/4")
• Multipose mounting
• Strong valve seat closing force 710 Newton
(160 lbs.)
• Compact size for easy installation in
confined area
• Field-configurable DIP switches for
Direct/Reverse action
• One device for either Vac or Vdc power
supply application
• Electronic current sensing provides internal
protection and positive full closing force
• Field-addable auxiliary switches available
GENERAL
The ML6874 is a self-contained, self-adjusting,
linear motorized linkage that mounts directly
onto V5011 two-way or V5013 three-way valves
and provides up to 19 mm (3/4") of linear travel
(stem lift). For use with low voltage 3-wire SPDT
Series 20 (on-off) or Series 60 (floating) controllers.
Contents
Specifications..........................................2
Order information................................... 2
Installation.............................................. 3
Wiring Schematics..................................5
Operation and Checkout.........................6
PCY 02/98
©
Honeywell Ltd. 1998 Printed in Canada
95C-10865
ML6874
SPECIFICATIONS •INSTALLATION
FIG. 1 -- DIMENSIONS OF ML6874 VALVE ACTUATOR IN MM (INCHES).
Installation
Mounting:
1. Ensure that the valve body is installed correctly, that is, the
arrow points in the direction of the flow.
2. Although the actuator can be mounted in any position, it is
preferable that the ML6874 is mounted above the valve
body. This will minimize the risk of damage to the
ML6874 in the event of condensation or a valve gland
leak.
3. Remove the stem button (Fig. 3) from the valve stem. Save
the set screw inside the stem button for later installation.
The button itself is not needed.
4. Slide the position indicator (plastic disk or rubber O-ring)
over the valve stem. (See inset, Fig. 3) Indicator will self-
align to the marking on the yoke after one complete
operating cycle.
Assembly of ML6874 to the valve:
1. The drive shaft of the ML6874 has a threaded hole to link
with the valve stem. Slide the yoke over the valve bonnet
(Fig. 4)
2. Thread the ML6874 drive shaft onto the valve stem all the
way, until it is completely attached (with no threads
showing), by turning the valve actuator in a clockwise
direction, as viewed from above (depending on the valve
models, use a pin or wrench to keep valve stem from
turning). Note that the valve actuator is shipped with drive
shaft in the mid-position.
3. Care should be exercised when using tools on the valve
stem during tightening. (Fig.4) DO NOT damage the
threads or other parts of the stem.
FIG.2 -- MINIMUM MOUNTING CLEARANCE.
CAUTION
1. Installer must be a trained service technician.
2. DO NOT electrically operate the ML6874
before assembly to the valve because damage
not apparent to the installer may occur.
!
4. Orient the conduit hole to the most desirable direction, then
tighten the LOCKNUTS on the U-bolt.
3
ML6874
INSTALLATION
FIG.3 -- PREPARATION FOR VALVE ASSEMBLY.
FIG. 4 -- ASSEMBLY OF ML6874A TO VALVE.
5. Remove the plastic cover from the ML6874 by loosening the
two screws located on the top (Note: These screws are captive.
Rotate three complete revolutions to remove cover ). Drop
either Slot Headed or Allen Hex type of set screw (both are
included in the plastic bag ) into the top of the shaft, slotted/
Hexed side up. Or use the set screw from the valve stem
button.
OR
Allen Wrench
6. Depending on which type of set screw was used, with a 5 mm
(3/16") Slotted screwdriver or 1/8"x 6" Allen wrench (included
in the plastic bag), tighten the set screw to lock valve stem in
place (Fig. 6).
!
WARNING
g
FIG. 6. -- LOCKING ML6874A DRIVE SHAFT TO
VALVE STEM
FIG. 5 -- U-BOLT ASSEMBLY.
4
ML6874
WIRING
3
SPDT
Controller
2
ML6874
1
W
T6
T5
W
L1
L2
R
B
24 Vac
R
B
OR
2
ML6874
+
T6
T5
W
T6
28 Vdc
W
R
B
R
B
T5
!
Caution:
In multiple actuators connection, power supply to all
actuators must be connected in a TRUE parallel fashion
to reduce excessive voltage drop. DO NOT "daisy chain"
i.e. connected to one actutator then branched to another.
Allow 0.5 amps maximum for each device. Actuators and controller can share same transformer providing the
VA rating of the transformer is not exceeded and proper phasing is observed.
1
2
3
Use configuration DIP switches to select device functions: Direct acting function (actuator stem moves upwards
with R & B closed ) or Reverse acting function ( actuator stem moves downwards with R & B closed ). DO NOT
reverse wiring.
SPDT controller can be a low voltage Series 20 "on-off " or Series 60 "floating" (center-off) type.
Configuration
DIP switches
located adjacent
to the input
FUNCTION
Direct Acting Mode
DIP SWITCH CONFIGURATION
on
off
on
1
1
2
2
3
3
4
4
terminal block
Reverse Acting Mode
off
NOTE:
Turn power off before setting the DIP switches.
Fig. 7 Wiring for SPDT controller to ML6874 actuators
5
ML6874
OPERATION AND CHECKOUT
Operation and checkout
Operation:
The recommended valve actuator power source is a class
2, 24V transformer or 28Vdc across terminals T5 &T6.
Internal circuitry provides dc power for the electronic
sensing and drive motor circuits.
REPLACEMENT NOTE:
1. The old ML684 actuators cannot be used with new
ML6874 valve actuators in the same circuitry, unless they
are isolated by an isolation relay to prevent cross-talking.
2. The ML6874 is a direct replacement for the old
ML684A1025 (160 lbs) in single actuator hook-up,
except when replacing the old reverse acting models, the
signal input wires to the new devices are no longer
needed to be reversed. Just set the DIP switch as shown in
Fig.7.
The motor is controlled by a microprocessor. Connecting
B to R tells the microprocessor to cause the actuator to
drive open, i.e. UP, in the Direct Acting Mode.
Connecting W & R will cause the actuator to drive closed,
i.e. DOWN, in the Direct Acting Mode. For "floating"
control, if R remains open, the actuator will remain in the
last position. The DIP switches are scanned only on power
up, and tell the microprocessor if Direct or Reverse mode
is desired. Changes in the DIP switch setting will only
take effect if the power is off while the change is made.
3. DO NOT replace the ML684A1009 (80 lbs ) with this
new ML6874 on the V5045 valve.
Checkout:( see General & Replacement Note )
1. Make sure the valve stem is completely screwed into the
actuator drive shaft with no threads showing.
2. Make sure the valve stem is locked in place with the set
screw.
At the end of the valve stroke, the actuator will develop
the necessary force for positive valve close-off. As forces
are developed, the current to the motor increases. The
microprocessor stops the actuator automatically when the
motor current, and forces reach the predetermined level.
3. Check DIP switches for proper setting for Direct or
Reverse Acting mode.
4. Connect R & B. Valves stem should move up, in Direct
Acting mode.
5. Connect R & W. Valves stem should move down, in
Direct Acting mode.
6. For Floating operation, open R connection. Valve stem
should remain in position.
7. Operate the system ( valve, actuator and controller ) for
several cycles to ensure proper installation.
8. When checkout is complete, return the controller to the
desired setting.
CAUTION:
1. Disconnect power supply before beginning installation
to prevent electrical shock and equipment damage.
2. All wiring must comply with applicable local electrical
codes, ordinances and regulations.
3. Make certain that the voltage and frequency of the
power supply correspond to the rating of the device.
4. DO NOT connect 24 Vac between any signal input
terminals.
!
5. DO NOT electrically operate the ML6874 before
assembly to the valve because damage not apparent
to the installer may occur.
GENERAL NOTE:
1. For correct valve operation, the ML6874 must be field
configured with the DIP switches which are located
beside the terminal block, see wiring diagrams for
details. Turn power off before setting the DIP
switches .
2. There is a short delay in actuator response upon every
signal change. It is to screen any unwanted incoming
signals.
3. For proper operation, voltage on the T5 & T6 must not
be less than 22Vac or 24Vdc during running or force
generating stages.
Home and Building Control
Honeywell Limited/Limitee
155 Gordon Baker Road
North York , ON
Home and Building Control
Honeywell Inc.
1985 Douglas Drive North
Golden Valley, MN 55422
Helping You Control Your World
Canada M2H 3N7
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