Sunday, January 17, 2016

Siemens SITRANS LUT400 Pump Level Assist Routines

Siemens SITRANS LUT400
Siemens SITRANS LUT400

The Siemens SITRANS LUT400 series controllers are compact, single point, long-range ultrasonic controllers for continuous level, or volume measurement of liquids, slurries, and solids, and high accuracy monitoring of open channel flow.

The preconfigured pump routines in the SITRANS LUT 400 allow you to choose the best pump control scenario for your application. In the video below, you will see how the assist pump routines work.

The SITRANS LUT 400 has three assists pump routines available:
  • Alternate duty assist
  • Service ratio duty assist
  • Fixed duty assist
The fixed duty assist routine mainly uses one pump to control the liquid level. In this example, pump 1 will always start before pump 2. When the liquid level reaches the pump 1 “on” set point, pump one will turn on. If the liquid level continues to rise while pump one is running, then pump 2 will start. Pump 2 will assist pump 1 to lower the liquid level. Both pumps we'll turn off when the liquid level reaches the “off” set point. This pump sequence is fixed. Pump 1 will always start first, then if necessary, pump 2 will assist pump 1.

The alternate duty assist routine rotates between both pumps to control the liquid level. Pump 1 will start first. If it cannot keep up with the inflow, then pump 2 will turn on and assist pump 1. Both pumps will run until the liquid level reaches the pump “off” set point. On the next cycle, pump 2 will be the first pump to start. Pump 1 will assist pump 2 if it is necessary. The starting pump will continue to alternate between pump 1 and pump 2 after each filling cycle.

The service ratio duty assist routine rotates between both pumps based on the defined service ratio. In this example the service ratio is split equally between both pumps. The SITRANS LUT will choose which pump starts first based on this ratio. Since pump 1 has the lowest runtime hours it starts first. Pump 2 will assist pump 1 if the level continues to increase.  On the next cycle, pump 2 to will start first. Pump 1 will assist pump 2 if necessary. The service duty ratio assist routine will continue to maintain the runtime ratio for each filling cycle.