Local control unit
Local control serves for controlling the actuators from the site of their installation. It consists of two selector
switches: one with positions "Remote control - Off - Local control", the other with positions "Opens - Stop - Closes".
If required by the customer, the actuator can be fitted with a blinker that produces electrical pulses during output
shaft rotation. For the blinker, no power supply has been built in the actuator.
Description and function of control units
a) Torque-limit switching
As shown in Fig.3, the torque-limit switching unit forms an independent assembly group consisting of the base
plate -19- which carries microswitches -20-, while at the same time providing for bearings of the torque control shaft
-22- and the locking shaft -29-.
The torque control shaft transmits movements of the floating worm from the power transmission gear tothe CLOSE
torque-limit microswitch (MZ) or the OPEN torque-limit microswitch (MO) by means of segments -23- or -24-
and levers -45- or -46-. The amount of limit-switching torque can be adjusted by the segments being turned with
respect to the tripping levers.
For readjusting the amount of the tripping torque outside the factory, the segments -23- are provided with a scale
on which the points of adjusting the maximum and minimum torques have been graduated individually for each
actuator, the adjusted torque being indicated by slots in the segments -27- and -28-. However, the numbers on
the scale provide no direct indication of the tripping torque adjustment, but the scale divisions serve only for a more
accurate division of the band between the points of maximum and minimum tripping torque and thus for more accurate
adjustment of the torque outside the factory in a location where no loading stand is available. The segment -23- is
designed for the OPEN direction, whereas the segment -24- is designed for the CLOSE direction.
The torque control unit is also fitted with a locking mechanism. On operation of the torque limiting switch, this
mechanism locks this switch and thereby precludes the switch from being reclosed and thus prevents actuator pulsing.
Moreover, the locking mechanism prevents the torque-limit switch from opening after reversal of the actuator and thus
makes possible full utilization of the starting torque of the actuator. The locking mechanism acts in either direction of
the output shaft motion of the actuator in the end positions as well as in the intermediate positionfor the duration of 1 to
2 revolutions of the output shaft after reversal thereof. With the output shaft of the actuator loaded at a reversed torque,
the torque control shaft -22- and thus the segments -23- and -24- turn by a slight amount. This displacement is
7
Diagram of microswitches
Legend:
19 – Base plate
20 – CLOSE and OPEN torque–limit switches (MZ, MO)
21 – Shifting device
22 – Torque control shaft
23 – Upper CLOSE segment
24 – Upper OPEN segment
25 – CLOSE lock screw
26 – OPEN lock screw
27 – Lower CLOSE segment with cut–out
28 – Lower OPEN segment with cut–out
29 – Locking shaft
44 – Lock nut
45 – OPEN tripping lever
46 – CLOSE tripping lever
The encircled numbers correspond to
the numbers of terminals on the terminal
board of the actuator.
The microswitches can be used only as one-
circuit devices.
19
20 29 21 23 25 27
45
22
44
24
26
28
46
12
10
13
11
1
2
Fig 3 -
Unit of torque switching
Содержание MODACT MON 100/130-100
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