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MODULE FOR AUTOMATIC CONTROL
OF AN ELECTRICALLY OPERATED VALVE
A module for valve control is a necessary component between the final control element – the valve with its actuator – and the computer system for the remote control.
The module is provided with its own independent controller, which ensures performing the following functions:
- power supply and protection of electric circuits and valve actuator motor, - selection of the operation mode: local control / remote control,
- local control of valve opening/closing,
- local signaling of the actuator operation state and valve opening/closing,
- remote control and monitoring of the valve operation using signals transmitted via a communication link from the local controller to the central control system.
The module is the best solution, from the viewpoint of technology and economy, for installations and systems where remote controlled fittings operating in the open-closed mode are used. Optionally it is also possible to use the module for control of the degree of valve opening/closing.
Two design versions of the module are available:
- for outdoor use – in a separate steel housing with IP65 degree of protection (the housing can be made of stainless steel), to be installed in the facility near the valve. Optionally the housing can be made of plastic,
- for indoor use - in a separate steel housing with IP44 degree of protection or as modules in a control cabinet for many valves.
Advantages of using the control module:
- matching together the actuator and control is ensured by the manufacturer. The module can control actuators made by different manufacturers.
- simplified installation in the facility – less wiring (the power supply and communication link only), - standard application diagrams available,
- communication with the remote control master system using the commonly adopted standard protocol,
- an actuator with the control is ready for start-up in the facility immediately after connection of power supply,
- programmability of the module allows one to quickly adjust the functions to changed requirements or operating conditions.
2 Examples of system solutions:
Fig. 1 – Diagram of control module connections with the valve actuator
Napęd zaworu – Valve actuator Moduł sterowania zaworu – Valve control module Zasilanie – Power supply Grzanie - Heating
Moduł logiczny sterujący – Logical control module Panel sterowania lokalnego – Local control panel
Otw. – Open Zam. – Close
Otwórz - Open Otwarty – Open Zamknij – Close Zamknięty - Closed
Awaria – Emergency Lokalne – Local Zdalne – Remote
Zdalne sterowanie – Remote control Wyłączniki krańcowe – Limit switches Ograniczniki momentu – Torque limiters Przeciążenie silnika – Motor overload
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Fig. 2 – Diagram of valve control module field connections
Obiekt – Facility Sterownia – Control room
Zasilanie – Power supply Nadrzędny … - Master system for control and visualization lub – or Sterowanie zdalne – Remote control
Moduł sterowania zaworu – Valve control module Panel sterowania lokalnego – Local control panel
Napęd zaworu – Valve actuator Zawór – Valve
Zawór z napędem … - Electrically operated valve with a control module
4 Functions performed by the control module
A) Power supply and protection for the actuator and control system:
Power supply available from mains, single-phase 50 Hz 230 V or three-phase 50 Hz 400 V (depending on the type of electric motor used for the valve actuator), is only required. No additional power supply for the control system is needed.
B) Selection of the control mode “Local – Off – Remote”:
It is done with a changeover switch in the control module. The switch is mechanically locked to prevent unauthorized change of the mode of operation.
- “Off” position – the actuator completely locked,
- “Local” position - the actuator may only be controlled with the aid of control module push-buttons. Remote control is locked.
- “Remote” position - the actuator may only be remote controlled. Local control is locked.
C) State of valve operation is signaled with lamps in the control module:
- lamp “Valve open” (Zawór otwarty) – lit continuously, when the valve is fully open, flashing when the valve is being opened,
- lamp “Valve closed” (Zawór zamknięty) – lit continuously, when the valve is fully closed, flashing when the valve is being closed,
- lamp “Valve stopped” (Zawór zatrzymany) – lit continuously, when the valve was stopped by the operator, flashes in case of emergency.
The signaling lamps in the control module are active both for the remote and local control. D) Local control by means of pushbuttons mounted in the control module:
- “Open” (Otwórz) pushbutton – when pushed, activates valve opening up to the fully open position (pulsed signal)
- “Close” (Zamknij) pushbutton – when pushed, activates valve closing down to the fully closed position (pulsed signal)
- “Stop” pushbutton – when pushed, interrupts valve operation and stops it at the current position (pulsed signal).
Control with pushbuttons is only possible when the “Local” control mode has been selected. E) Remote control from the master system:
After selection of the “Remote” control mode with the changeover switch in the control module the local control becomes locked and a signal ‘ready for remote control’ is sent to the master control system. A serial connection with the PROFIBUS communication protocol is used for transmission of remote control signals.
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Typically the following signals to/from the master control system are foreseen: - valve state signaling – open/closed
- control mode signaling – remote control
- emergency signaling – no response to a command - valve control commands – open/close
- power supply failure.
Technical parameters;
Overall dimensions of the control box - HxWxD – 300x300x1200 mm (overall dimensions for actuators of 1.5 kW max.),
Degree of protection – IP65,
Mounting – on a supporting structure or on the valve, front access to the apparatus, cable access from below,
Paint color – RAL 7035,
Environmental conditions – from -20°C to +45°C, Power supply voltage – 50 Hz, 230 V or 3~50 Hz, 400 V, Current, max – 8 A (depending on the actuator size),
For actuators of higher power the overall dimensions and currents are larger.
Standard of execution – the control equipment of recognized world’s manufacturers of electric equipment and controllers.