HLA paddle switches on power station ash hoppers

Emerson has supplied 180 Mobrey Series PLS paddle switches to the Polish ash filter manufacturer, ELWO, for use as high level alarms in ash hoppers at two Turkish power plants

The ELWO hoppers are being installed as part of the modernisation of electrostatic precipitators at two Turkish power plants.

The simple and reliable switches, which are easy to install, alert the operators at the Soma Power Plant and Seyitomer Power Plant when the levels of ash in the hoppers reach an unsafe level.

This prevents hopper overfill, which would have significant impact on the operation of the plant, and allows operators to ensure they have emptied the hoppers as required to keep ash within safe limits.

The robust PLS Series were selected for this application because they provide good reliability in the harsh conditions of a power plant.

Temperatures reach in excess of 200C: no problem for these Mobrey high temperature models, which are available to withstand working conditions of 400C.

"We are pleased to support ELWO and also the Turkish power plants by supplying this large international contract for critical applications," said John Walsh, product manager of the Mobrey measurement division of Emerson.

"It is an opportunity to combine our technology and support to serve Turkey and the Eastern European markets.

The first installation was completed six months ago and the switches have proven very reliable.

We have just completed the second installation".

The Mobrey Series PLS paddle switch can be used as either a high level switch with materials over 160kg/m3 or as a low level limit switch for dry and solids products over 80kg/m3.

It is easily mounted through the wall of the vessel with the paddle extending inside.

An electric motor drives a paddle which rotates freely in the absence of solid material (ash).

Rotation of the paddle is prevented when covered by the ash and the motor rotates inside the housing to actuate a microswitch and signal an alarm.

A unique clutch mechanism automatically shuts off the motor, which extends its life.

Once the material level falls, the motor is returned to its normal position and the paddle begins to rotate.

The Mobrey paddle switch has standard models operating to +150C and high temperature models are available to 400C.

The switches are available with options for easy installation, including, extension shafts for top of silo mounting, and mounting plates.

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