Commissioning Solutions Scotland Ltd.

01463 710 503

The Company with a Balanced Approach

Industry Leading Software Developers

Unitronics Siemens Technology Used

Technical excellence, attention to detail and experience enable us to provide cost effective solutions within the required timescales solving our clients problems and satisfying their requirements.

We draw on knowledge and experience gathered over decades and have excellent electrical and mechanical support from our in-house team using SCADA, PLC's or microcontrollers as appropriate.

Pick up the phone and give James a call on 01463 710 503


Working with unitronics has been really interesting, but most importantly it's been a very positive experience.

Case Study No 1 - MacDuff Shellfish - Monoscreen pumping system.

For some time, waste effluent from Macduff shellfish processing lines was being transported to a nearby site for further treatment. Our new scheme is designed to remove small pieces of meat, shells, sand, silt and labels.

The screening process uses a 2mm monoscreen technology to lift the debris out of the channel and convey it to a higher level which enables it to gravitate down a launder shoot into a sealed skip.

Effluent from the process lines flows into a common drain pipe and gravitates into the inlet pumping station which comprises of the following equipment;

- A pair of vortex type variable speed pumps duty standby on guide rails.

- One high level float for generating a high level alarm.

- A radar level transmitter for normal control.

- Three actuated pinch valves to provide scouring and channel selection.

Case Study No 2 - MacDuff Shellfish - Waste Water Pumping System.

As part of MacDuff Shellfish expansion they have nominated CSS to provide the equipment and control to enable them to discharge variable flows at varying times from a new Condensate Pumping Station.

Condensate is removed from a number of condensers within the factory and piped to a new pumping station. In the pumping station sump is a new variable speed 3 phase pump on guide rails, radar for level control, a suction pipe from the Hydro Auto sampler and a Flow Meter is located above ground on the discharge pipe to the sewer.

Provided that the sump hasn’t reached the low setpoint (SP1) and no alarms exist then the variable speed pump will be run at the flow rate determined by the consent document. The Flowmeter will provide a 4-20mA closed loop feedback which will be used to control the speed of the pump using a PID algorithm to the desired setpoint flows.

Both the instantaneous flow and the totalised flow must be logged and stored every 24 hrs. The totalised flow must automatically reset on a daily basis. The data must be stored in a way so that it can be recovered at a later date.


Siemens are an Incredible Company within the Engineering Sector. We have worked on numerous projects which involve Siemens PLC, HMI and SCADA systems.

Development screen for Aeration and Dissolved Oxygen

1. Waste Water Treatment Works - Dissolved Oxygen problems

Our client was having an issue regarding Dissolved Oxygen Control within their settlement tanks at their Waste Water Treatment Works

We were recruited to investigate and resolve these issues alongside a new installation of Variable Speed Drives

Our job was to re-write the PLC program to accomodate the new VSD control with Analogue outputs, as well as update the local HMI with some options for the on-site operators to be able to control the level of Dissolved Oxygen within the Settlement Tank

The version of software that we initially started working with was configured to output a Digital signal to the VSDs so they would run either 0 or 100%. With the new modifications regarding Analogue output, we are now able to run the VSDs with a cotrollable PID loop which ranges within a base of roughly 60%, up to a maximum of 90%.

The reason for a base of 60% and max of 90% is:

Part of the job requirement is to have the VSDs always run at a constant base speed in order to keep the settlement tanks moving, which in turn will keep the levels of MLSS at a reasonable level.

The max level was discussed and confirmed to be 90%. This is so that the Aerators do not run too fast, causing excessive splashing of settlement tank liquid

Development screen for Aeration and Dissolved Oxygen Setpoint Control

Technologies Used.

Programmable Logic Controllers.

Programmable Logic Controllers (PLCs) are the mainstay of industrial automation and we are well versed in all major brands. We regularly work with Siemens, Allen Bradley and Mitsubishi, but also use other brands such as Omron, Modicon and Unitronics when applicable.


In tandem with the PLC some form of operator display is often required. This can take the form of a touch screen hardened to withstand harsh industrial environments such as a AB Panelview or Siemens Comfort Panel.

If more detailed process information and/or better reporting is required we will install a SCADA system such as InTouch or Iconics. This can be set up to run on an normal pc however industrial PCs can be supplied if the application demands it.

Other Technologies

We are able to supply other types of automation ranging from PC based control systems such as LabView to smart relays and embedded micro-controllers if that is what the application requires.

Back to the top