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Limiting conditions:
1. Cable bushings OS and O can only be used for braided cables and firm instruments; the cable should be properly
fixed to prevent its possible pulling out or twisting.
2. Operating temperature of the cable bushing is -60 °C to +80 °C.
3. The space between the equipment and the cable bushing should be sealed in order to preserve particular degree
of protection against penetration of dust, solid particles, and water.
Accessories:
Before assembling or dismounting the cable bushing, become familiar with accessories of the cable bushing which
include, for instance:
– coat providing additional protection against corrosion;
– safety nut securing position of the cable bushing;
– sealing washer under the additional protection of the cover of the cable bushing front part against penetration;
– knurled washer damping vibrations that could loosen the safety nut or the cable bushing assembly
The inlet to the actuator and connection to its switching, protection and securing instruments can only be installed by
technicians with particular qualification who must follow pertaining standards and wiring diagrams as provided in these
Instructions for Use. After connecting the inlet cables, all screws of the connecting terminals should be checked for tightness
so that they do not get warm during operation due to increased transition resistance. The connecting terminals must not
be under tension or bending stress from the connected conductors. In case of connection with aluminium conductors the
following measures are recommended. One-step before connecting the conductor, the oxidized layer should be removed
from the conductor and new oxidation should be prevented by smearing the connection with a neutral vaseline.
After the connection, make sure, by short starting of the actuator in the intermediate position of the working stroke,
that the output shaft of the actuator rotates in a proper direction. If this is not the case, reconnect any two conductors
on the terminals U, V, W of the motor (actuator) terminal board. Then, repeat the functional check. After verifying correct
electric connection, the actuator is fitted to the valve and adjusted according to the paragraph Actuator Setting. The
adjustment is best carried out using the manual control mode.
Important warning!
1) During adjusting, repair, and maintenance, secure the actuator in the prescribed way in order to rule out its connection
to the power supply and thus to prevent possibility of an injury due to electric shock or the actuator rotation.
2) When the thermal protection is disconnected, is necessary to realize that – if the power supply is on the terminals
– after cooling of the thermal protection the actuator will start automatically.
After adjusting the actuator check its function by means of the control circuit. Especially check whether the servo
actuator correctly starts up and whether the electric motor after turning off the respective relay is not energized. If not,
switch off the actuator power supply off immediately to prevent damage to the electric motor, and find the case of the
fault.
10. OPERATION AND MAINTENANCE OF ELECTRIC ACTUATORS
Operation of the electric actuators results from the operating conditions and, as a rule, it is limited to giving
impulses to respective functional tasks. The electric actuator can be controlled electronically in remote way as well
as manually on site of the installation. Manual control is possible by means of a hand wheel of the electric actuator,
it does not require any change-over switch and can be used without any danger to the staff even in case that the
electric motor is running.
The operator should take care that a prescribed maintenance is carried out, the electric actuator is protected
against dangerous effects of the environment and weather conditions which are not listed in the chapter
“Working
Conditions”.
Moreover, care should be taken to prevent abnormal heating-up of the surface of the solid closure of
the electric actuator. Make sure to avoid exceeding the nameplate values and abnormal vibrations of the actuator,
maintain quiet operation of the actuator, ensure proper tightening of bolted joints of the parts of the flameproof
enclosure, check insulating state after a longer break Sometimes it is necessary to make sure that all connecting and
earthing terminals are tight and that they do not heat up during operation.
Maintenance
The maintenance of electric actuators lies in possible replacement of defective parts. Grease filling is stable for
the electric actuator service life, i.e. 6 years. If the electric actuator is capable of operating even after 6 years the old
grease should be taken out from the power part and new grease filled in.
After 6 months at most from putting the electric actuator into operation and then at least once a year, the connecting screws
between the piping fitting and the electric actuator should be retightened. The screws are tightened in a crosswise manner.
