Multi-turn electric actuators of the enhanced safety for nuclear power stations as per TC 3791-006-05749406-2000, types M, A, Á, Â, Ã and Ä with a double-sided torque coupling are produced since 2001. These products are supplied to the nuclear power stations of China, Iran, Russia, and the UIS in large number.
A number of parameters have been improved:
- 1. The service term and the reliability of the electric actuators have been prolonged and improved.
- 2. A more precise adjustment of the switches set has been provided due to the increasing of the range number from three to nine.
- 3. The availability of the swift-action mechanism in the switches set provides for:
- a) absence of the micro-switches “blockage” effect;
- b) “momentary” (0.1 rotation of the output shaft) restoration after the actuation of a limit switch, which immediately gives information to the operator about the beginning of the valve gate motion.
- 4. The availability of the valve gate position indicator (VGPI) provides for:
- a) linear signal supply 4…20 Ma with the 2.5% linearity during the valve gate motion;
- b) “emergency” signal supply (24Ma) at more than 7% beyond the extreme positions movement.
- 5. The availability of the modern terminal set with a spring clutch (WAGO type), which guarantees a reliably engaging of the electric actuators with the section of 0,08…2,5mm2.
- 6. The electric actuators serviceability at more severe parameters of the environment (in emergency cases).
The electric actuators are designed to complement special pipeline valves, installed in any systems and industrial premises of the NPSs with BBÝÐ-1000, ÐÌÁÊ-1000, ÐÌÁÊ-1500 reactor.
The electric actuators provide for:
- a) closing and opening the valve passage, stopping the valve gate in any intermediate position:
- by any remote control,
- directly from the electric actuator (with the MSS available);
- b) warning signal of the extreme and intermediate positions of the valve gate on the control board and actuation of the break-down torque coupling:
- for the electric actuator control,
- for signaling the condition of the electric actuator on the indicator board;
- c) indicating of the degree of the valve passage opening on the control board in the block control board (BCB) and the reserve control board (RCB) for the position indicator electric actuators versions supplied upon the customer’s request;
- d) automatic change-over of the electric actuator from manual handling to electrical handling or independent manual and electrical handling;
- e) local indication of the extreme and intermediate positions of the valve gate on the local indication scale (for extra-shell versions);
- f) elimination of the self-motion of the valve gate under the influence of the environment in the pipeline.
Upon the customer’s request the electric actuators to be mounted outside the shell are supplied with a local control board (LCB), which is fastened to the body of the electric actuator.
The LCB performs the following functions:
- giving commands for switching the electric actuator on and opening of the valve gate;
- giving a command for stopping the valve gate in any intermediate position;
- signals the readiness of the LCB to control the electric actuator, as well as of the position of the valve gate in one of the extreme positions (“Open” or ”Closed”).
The electric actuators are also supplied with the signaling apparatus of the valve gate position (SAVGP).
The valve SAVGP has the exit signal from 4 to 20 Ma, linearity +/- 2,5% with the full resistance of the loading from 0 to 500 Om and ensures a comfortable adjustment during the electric actuator mounting.
A universal transformer of the analog signal (UTAS) is used together with the position indicator (two-section complete-turn resistor) as the SAVGP.
