Control of electrical control valves in power stations

The application

Central control, conventional actuator  

Power station

Valves are used in process environments for the control and regulation of mass or energy flows. They change the resistances in pipeline systems either continuously or in stages in accordance with the requirements of the process. 

Use of control valves

Electrical gate valves  

Valve with actuator

In contrast to control valves, regulating valves used for limiting mass flows are neither fully open nor fully closed, but rather regulate the required flow in an analog manner. In power stations, regulating valves are used primarily in steam and water circuits or as condensate drains for normal operation.

If no analog regulation is required, control valves are used. Today, power stations use a range of different drive forms and types for control valves, resulting in a variety of energy supply concepts.

Central control, conventional actuator

Central control, conventional actuator  

Central approach: Conventional actuator - Control via low-voltage main distribution

Here, the control valve is controlled from a central switchgear. This central switchgear contains the motor protection, the fuse protection, and the reversing contactor combination for controlling the control valve. The reversing starter is controlled via the central automation system.

This system configuration is expensive, extremely cost-intensive, and also requires a huge amount of cabling to the control valves.

Control via fieldbus, actuator with integrated motor control

Control via fieldbus, actuator with integrated motor control  

Distributed approach: actuator with integrated motor control

In many new power stations, control valves with integrated motor starter functionality and control via PROFIBUS DP are used. Within the scope of this concept, the energy is often supplied to the control valves via decentral energy distributing stations.

This system configuration involves substantial outlay to ensure EMC-safe cabling and a high level of investment due to the more complex control valves.

Increasing cost pressure, combined with the need for consistently high availability, calls for new supply concepts and solutions.

The solution

Control cabinet, distributed control valve station  

Structural diagram: Distributed control valve station

With its distributed control valve station, Phoenix Contact offers a technical solution for the distributed supply and control of control valves. The switching actuators and feedback from the switch position are controlled via an I/O module with PROFIBUS DP connection that is connected to the automation system. A media converter converts the fiber optic technology to wired transmission technology inside the station. The CONTACTRON technology from Phoenix Contact enables a control valve to be controlled with a nominal current of up to 9 A.

CONTACTRON combines four important functions in one device: forward running, reverse running, emergency stop, and motor protection - and all this with an overall width of just 22.5 mm. The safe protection of the motor against overload is achieved with CONTACTRON via a Class 10a characteristic curve in accordance with IEC 60947. CONTACTRON also meets coordination type 2 in accordance with IEC/EN 60947-4-2. A 24 V power supply combined with the intelligent ORING redundancy module supplies the distributed station and guarantees maximum availability. The individual main current and auxiliary voltage fuse protection on each control valve enables a drive to undergo a targeted activation process.

 

Independent system configuration

Actuator, distributed motor control and PROFIBUS control  

New system configuration: the perfect combination of actuator, motor control, and distributed PROFIBUS control

This autonomous system configuration considerably reduces cabling and engineering costs. It also makes it possible to operate the control valves on-site and paves the way for simplified maintenance.

Phoenix Contact not only offers all of the necessary components, but also provides you with complete solutions for a new system configuration. The distributed control valve stations required for this are pre-assembled, fully wired, and ready to connect.

Your advantages at a glance

  • Reduced number of central switchgear and associated space requirements
  • Cost-optimized solution with high availability
  • EMC-safe cabling with reduced cabling effort
  • CONTACTRON saves space and therefore costs
  • Ready-for-assembly, pre-wired control valve stations

PHOENIX CONTACT (Ireland) Ltd

C6 The Exchange
Calmount Park
Ballymount
Dublin 12
D12 XE18
Ireland
(01)2051-300

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