Bernard Controls EZ Serie Inbetriebnahmeanleitung Seite 9

Travel limit switches description and function:
The cams operating the limit switches are on a cylindrical block which does not require any disas-
sembly. Each cam can be set independently of the others. The white and black cams are for OPEN
and CLOSE travel limit switches. The other cams actuate additional limit switches (Example : For
signalling).
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.
b) Manually drive the valve to the closed position. 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) Turn stop screws clockwise to the mechanical contact, reloosen 1.5
turn, and secure by lock nut.
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.
4.3 position feeDBack potentioMeter (option)
The potentiometer used for actuator signal feedback is driven by the travel cam block system.
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.
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On support column mounted version (EZ4 to EZ15 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.
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.
Signal inversion:
To inverse the signal variation direction, invert potentiometer wires on the actuator terminal board
(e.g. for a connection on 16/17/18, invert 16 and 18).
4.4 «taM» position transMitter (option)
The TAM transmitter delivers a 0/4 to 20 mA signal linearly proportio-
nal to the angular position of the valve.
Electric connections
Refer to the wiring diagram supplied with the actuator.
FIltered or stabilised power supply should be provided within the 12
to 32 VDC range. Maximum admissible ohmic load values are given in
the table :
Energy Supply Max. admissible
DC (VOLT) load Ohm
12 150
24 750
30 1050
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