Application Story

Pump It Up!

Moeller control relay aids effective float-activated sewage pumping

Based in Bury St Edmunds, Suffolk, leading pump specialist Bury Pumps Ltd supplies a variety of pump solutions for a wide range of applications. When it came to the precision control of its new packaged pumping chamber, Bury Pumps turned to Moeller Electric and its innovative Easy control relay.

The twin or triple pump chamber uses a system of float switches linked to an Easy to regulate pumping, giving a clean and efficient solution for sewage and waste water removal, where the source is below main sewer level. The ready-to-install pumping chamber comprises a tank containing pumps, control panel, valves and pipe work. This design is ideal for a wide range of applications from individual houses, to small housing estates, industrial estates and small sewage treatment plants.

Bury Pumps' Engineering Manager, David Vickery, said: "Easy's simple push-button programming and rugged construction make it ideal for this type of application. Our customers need a reliable field programmable solution, requiring the minimum set up time and maximum flexibility."

The twin pump unit uses two float switches. When the waste liquid level rises to the first float this signals the Easy to get ready to operate the pump. On the second float switch being triggered, Easy activates one or both pumps. Under normal operating conditions one pump is enough, with Easy programmed to switch on either pump, providing even pump ware. However, if the rate of inflow of waste water is very high, for example during heavy rain, then both pumps are triggered to operate simultaneously. When the waste water finally drops below the first float this stops the pumps. This two float switch system is designed to prevent intermittent switching which would burn out the pump motors.

A triple pump system with a third float switch to activate the additional pump is available for demanding applications with very rapid inflows of waste water. Again Easy controls the pump operation.

A combination of Easy 600 and 412 series units are used in the design. The 600 series provides twelve inputs and six relay or eight transistor outputs, while the Easy 412 has eight inputs and four relay outputs. Expansion modules are available for the 600 series, giving a maximum of 24 inputs and up to 16 outputs. A communications module option provides remote control of the relays.

Programming Easy couldn't be simpler and is carried out through keystrokes that are then displayed on an LCD screen. The 412 series allows up to 41 lines of logic, the 600 series up to 121 lines of logic. This provides sufficient space for a whole host of applications and for any subsequent modifications and extensions. Rapid set up and programming is facilitated by Easy Soft, which allows the development of programs on a PC prior to downloading to the unit.

In the event of power failure, Easy remembers not only circuits and parameters but also retains switch positions and values. For example, the actual value on the counter and the elapsed time on the timing relay can be recorded. Thus it is very simple, for example, to implement operational hours counters. These tough units are able to tolerate temperatures between -25ºC to +55ºC, allowing them to operate in the most severe of conditions.

This page last updated: 8 September 2001