Setting Of Mechanical Stops And Travel Limit Switches; Setting Of Torque Limit Switches; Position Feedback Potentiometer (Option) - Bernard Controls oa Anleitung Für Die Inbetriebnahme, Lagerung Und Wartung

setting oF MecHanicaL stops anD traveL
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LiMit switcHes
Mechanical stops description and function (1/4 Turn only):
These items avoid any over-travelling during handwheel operations.
The stops can be positioned either on the actuator itself or on the 1/4 Turn
worm gearbox if any.
Actuators and gears are supplied and tested for a 90° operation.
Fine adjustment of the stop screws position is possible within a limit
of ± 2° maximum.
Travel limit switches description and function:
The cams operating the limit switches are on a cylindrical block which
does not require any disassembly. Each cam can be set independently
of the others. The white and black cams are for open and close travel
limits. The other ones are for optional additional limit switches (2 or 4).
How to operate the cams:
a) Put a screwdriver in the slot of the button encircled by the same
color as the cam to be set,
b) Press lightly to disengage the cam of locked position,
c) By turning the screwdriver rotate the cam to the position in which
it can trip the limit switch,
d) Remove screwdriver and ensure that the button has come back to
its original position, thus locking the cam in chosen place.
Procedure of mechanical stops and travel limit switches setting:
a) Loosen stop screws by 2 turns (1/4 Turn only).
b) Manually drive the valve to the closed position. For the 1/4 Turn
devices, if mechanical stops are reached before the valve closing
is completed, it means that the 2° maximum adjustment tolerance
has been exceeded ; do not try to go beyond this limit.
c) Set the cam of the «CLOSED» travel limit switch.
d) T urn stop screws clockwise to the mechanical contact, reloosen
1.5 turn, and secure by lock nut (1/4 Turn only).
Proceed in the same way in open position.
Perform complete electrical valve opening and closing operations.
It is mandatory that the motor stops on the travel limit switch and not
on the mechanical stop (check available extra travel to the stop with
handwheel).
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6 setting oF torque LiMit switcHes

IMPORTANT: the torque limit switch design of Bernard Controls actua-
tors gives a short duration contact only. On request, relays holding this
contact maintained can be fitted into the actuator.
Actuators are set and tested in accordance with the torque stated
on orders. If no torque is specified, the actuator is supplied with torque
springs set to the maximum output (refer to our catalogue technical
datasheets).
If necessary, this torque setting can be readjusted by rotating the nuts
which compress the torque springs. So the torque can be increased
or decreased by tightening or loosening the nuts. Please consult us.

7 position FeeDBack potentioMeter (option)

The potentiometer used for actuator signal feedback is driven by the travel
cam block system.
The potentiometer has no mechanical stop and has a non-resistive area
(dead zone) at both the beginning and end of track.
0% position corresponds to a closed valve. 100% to an open valve.
Circuit board mounted version
To mount the potentiometer device on the switch plate, clip it without
the position indicator on the camblock and screw it on the support
column. Screw the position indicator back.
Setting of potentiometer zero is achieved thanks to the «0% postion»
screw.
Drive the actuator to the closed position.
Resistance value is measured between terminals 16 and 17.
Hold the pinion located just under the plate with the «0% position»
marking while driving the potentiometer screw. Adjust the potentiome-
ter so that the resistance value exceeds 0 Ohm and regularly increases
then turn backwards to reach a value as close to 0 Ohm as possible.
Drive the actuator to the open position and write down the resistance
value corresponding to the 100% position.
Come back to the closed position and check that, for the 0% position,
the resistance shows a close to zero repeatable value.
On support column mounted version (OA type of actuactors)
To mount the potentiometer device, screw the support column on the mounting
plate and engage the driving pinion into the camblock wheel.
To adjust the potentiometer resistance value, loosen the nut with the wrench
and rotate potentiometer until the signal requested is archieved.
To set the 0%, drive the actuator to the closed position.
Resistance value is measured between terminals 16 and 17.
Rotate the potentiometer so that the resistance value exceeds 0 Ohm
and regularly increases then turn backwards to reach a value as close
to 0 Ohm as possible.
Retighten nut after setting.
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