Water Treatment

8 x Rectangular Distributors 

Overview.

UCS Automation supplied a complete electrical control solution for the Cantilever Distributors at a STW project comprising:

• Control of 2 x synchronised Drives controlling the speed of the Distributor.

• Control the Distributor to slow down at the end of each directional travel, before changing direction.

• Anti-collision control of the Distributors.

• Summer / Winter mode control.

• Single / Dual operation mode control.

• Filter Bed Flushing Cycle.

• Flow monitoring.

• Over-travel protection.

• Travel monitoring timer.

• Emergency Stop(s) to remove power to the Drives utilising a safety monitoring relay.

• Alarm Beacons.

What was developed?

Filter Bed Distributors giving 100% coverage of the Filter Bed along with seasonal (Summer / Winter) modes. Use of a number of distributors on one Filter Bed.

What previously existed in this field?

A limited distribution of the filtrate onto the Filter Bed and limited flexibility on the control of the system.

What is the advance / appreciable improvement?

Due to the extra distributors on each filter bed, the system had increased flexibility on a continual coverage.

What were the technological uncertainties?

There were two uncertainties to resolve these were:

1 – How to stop the Distributors from hitting each other during overlapping.

2 – How can the Distributors travel without ‘crabbing’ using independently driven motors on each Distributor.

3 – Making the Distributors cover the filter bed efficiently, even if only one Distributor was in use required some research into a better solution than that provided by the manufacturer.

During the commissioning we were thrown another problem of how to keep the system running in temperatures below 0o. Something the mechanical design engineers had not accounted for during the design of the 400V mains supply busbar.

How and when were the uncertainties resolved

1 – After trials with laser sensors aimed at small targets on each distributor, UCS had to abandon this idea and the final solution involved ultrasonic sensors aimed at larger targets.

2 – The final solution to avoid ‘crabbing’ involved making one of the motors a ‘master’ and the other a ‘slave’. With encoders fitted to both ‘master’ & ‘slave’, the speed of each motor could be matched more accurately.

3- Software modifications along with trials using differing lengths of strikers resulted in the best solution.

The busbar freezing was resolved by using a double carbon-brush system.

Testing of the software I/O control and SCADA was performed in the workshop environment before being installed and fully commissioned at the clients site. All further developments were made during the 10 days spent commissioning the system, these consisted mainly of enhancements & requests direct from the operator.   No limitations were encountered after the final commissioning.