Callidus Design Consulting Engineers

Designers, engineers, consultants and technical specialists covering a wide range of building and process services.

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Controls Engineering Design Services

Callidus Design has extensive experience of the successful design, specification and installation of Controls Engineering systems such as Building Management Systems (BMS), Building Energy Management Systems (BEMS) and Process Control Systems including SCADA (Supervisory Control and Data Acquisition) for PLCs. Applications include those which provide environmental control, process control and central plant control.

Two main fields of controls engineering have developed separately but concurrently:

 

Building Management System (BMS) - Building Energy Management System (BEMS)

These two terms are used interchangeably to describe a control system consisting of discrete controllers linked together using either a proprietary communications network (LAN or Local Area Network) or an open system such as ethernet. The controllers, or outstations, consist of a central CPU connected to the real world via Analogue and Digital Input and Output channels (I/O). Real world data is provided to the input channels from sensors and switches. Control of real world is achieved via the output channels to actuators, relays and drives. The central processor is programmed with a controls strategy which should match that envisioned by the original system designer. The activitiy of the connected systems is able to be viewed on both local HMIs (Human Machine Interfaces) or on networked PCs commonly referred to as the Front End or Supervisor. On the Fornt End, the operation of the controlled systems is represented by graphics depicting the main components and the status of each of the I/O. With appropriate programming, the graphics on the Front End can also remotely make changes to the outstation settings. The BMS is also used for the collection and storage of data and the transmission of fault conditions to operators via a range of communication methods such as email, sms and local audio and visual indicators.

PLC (Programmable Logic Controller) and SCADA (Supervisory Control and Data Acquisition)

As with BMS systems, the PLC consists of a discrete controller consisting of a central CPU connected to the real world via Analogue and Digital Input and Output channels (I/O). Real world data is provided to the input channels from sensors and switches. Control of real world is achieved via the output channels to actuators, relays and drives. The central processor is programmed with a controls strategy which should match that envisioned by the original system designer. Multiple PLCs are linked together using either a proprietary communications network (LAN or Local Area Network) or an open system such as ethernet.The activitiy of the connected systems is able to be viewed on both local HMIs (Human Machine Interfaces) or on networked PCs commonly referred to as the SCADA. On the SCADA, the operation of the controlled systems is represented by graphics depicting the main components and the status of each of the I/O. With appropriate programming, the graphics on the SCADA can also remotely make changes to the PLC settings.The SCADA is also used for the collection and storage of data and the transmission of fault conditions to operators via a range of communication methods such as email, sms and local audio and visual indicators.

Each of the controls engineering technologies have developed in parallel but for the most part have their own niche applications. Traditionally, BMS/BEMS has been used in smaller scale, non-industrial buildings for the controll of HVAC (Heating, Ventilation, Air-Conditioning) plant whereas PLC/SCADA has been used for industrial and process applicaiotns. However, as the two technologies converge, the line has become more blurred as each system vies for a slice of the other's market. 

Energy Monitoring and Targeting

Controls strategies play a vital role in maximising the efficiency of all mechanical and electrical systems. It is the application of more comprehensive controls packages which have led to some of the most significant advances in efficiency which we have witnessed it the past decade. Of course, control of plant or indeed energy cannot be achieved without first measuring and monitoring. It is the installation of a myriad sensors and sensing technologies which provide the controls systems with their 'eyes' and 'ears'. Only by monitoring energy consumption is it reasonable to expect to be able to reduce it.

Fault Monitoring, Investigation & Resolution

As well as the controls functionality itself, a BMS or SCADA provides a further critical function in the operation of complex processes, namely Alarm Handling. On a large site with a high I/O count, keeping track of the operational condition of the plant can be a substantial task. Once the process limits are programmed, the resulting alarms can be by marshalled and filtered by priority to enable the operator to distinguish those that need the most urgent attention. Logging of alarms and coincident operational conditions allows a high degree of fault finding and troubleshooting to be carried out from the Front End or Graphical Interface. This can save a significant amount of time on site as the maintenance team can be directed with more accuracy to the cause of the failure.

Critical Environments

State of the art production facilities increasingly rely on close control of critical environments to provide ideal conditions under which their manufacturing process can be carried out.. These include close temperature control as well as close humidity control environments (control range: <5%RH and >98% RH can be achieved where necessary). Temperature control of large spaces to within +/- 1DegC is now commonplace for close tolerance manufacturing processes.

Preventative Maintenance

As the sophistication of controls systems have increased ,so has their interoperability with complementary technologies. Control systems can now be integrated with preventative maintenance systems to improve the accuracy of maintenance targeting and thus reduce maintenance costs. Condition monitoring of plant components allows parts replacement on a qualitative basis rather than on breakdown or by timed forecasting.

Integration

Many items of mechanical and electrical plant are now being constructed with their own internal controllers. These controllers can be regarded as localised BMS or PLCs since they contain the same basic component parts. As such, the local controller in the plant can hold information which is valuable to the operator. In previous generations of the technology, the individual items of data would have been exported from the plant controller by Analogue or Digital Outputs (AO or DO). In turn, these signals would be routed to the Analogue and Digital Inputs (AI or DI) of the BMS or PLC controller for onward processing and display. However, the technology has advanced such that a direct communications link can be installed between the plant controller and the BMS/PLC controller. All of the data from the plant controller can now be relayd via comms to an interface module attached to the BMS/PLC instead of having to use I/O. There are several different types of communications bus available for this purpose e.g. BACnet, ModBus, LonTalk, Ethernet, RS485. Not all plant controllers offer the same options for the communications bus and therefore, multiple interface modules may require to be connected to the BMS/PLC each specific to an item of plant.

Controls Engineering Design Service

The above summary is a small selection of the controls engineering services we provide whether it is for design or non-design related applications. If you have an application requiring the services of Consulting Engineers for any controls engineering service, whether listed above or not, please don't hesitate to contact us via our Contact Us page.

Callidus Design Limited
  • Law House, Fairbairn Place
  • Livingston EH54 6TN
  • T: 01506 418188 
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