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Electronic Load Controllers

In hydel-turbines, the turbine RPM and hence the generator RPM which is connected to the turbine changes with electrical load on the generator as well as hydro-power input to the turbine.  This change in RPM results in change in frequency of the output.  It is not desirable to have frequency changes for most electrical loads.

Electronic Load Controller (ELC) is a state-of-the-art product that is designed to maintain a constant electrical load on the generator.  To keep the generator RPM and hence the output frequency constant, additional resistive electrical loads (heating elements) called dump loads are used.  The dump loads dissipate the surplus power generated and keep the generator RPM constant.  It is a stable feedback control system to keep the generator RPM and the output frequency constant.  The power dissipated through the dump loads can be used to heat water, heat agricultural products in ovens or for other purposes. To address the changes in generator RPM due to varying water flow, an Automatic Frequency Compensation (AFC) is provided, which maintains constant and stable frequency of the output.

We manufacture two variations, Power Controlled ELC and Voltage Controlled ELC.

 

a) Power controlled ELC:

Power Controlled Electronic Load ControllerPower controlled ELCs maintain a constant power output from the generator, irrespective of the user demand. The excess power is diverted to dump loads. They also maintain a constant frequency. To protect against changes in turbine RPM resulting in changing frequency, we use a feature called Automatic Frequency Compensation (AFC). This is a state-of-the art product with almost instantaneous response times. In conventional ELC's, which are controlling only frequency, the correction response is very slow. Also, they are thyristor based and result in waveform distortion, due to which the generator has to be de-rated. In our ELCs, power control as well as frequency control are employed which makes the system response very fast, thereby protecting user load from variable frequencies. Also, our ELCs have a perfect sine-wave output and no waveform distortion. We manufacture power controlled ELCs in the range of 3kW to 100kW for 3 phase as well as 1 phase.

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b) Voltage Controlled ELC:

Voltage Controlled ELCThese are generally used with permanent magnet generators (PMG). Voltage controlled ELCs maintain a constant output voltage. The dummy loads are controlled with PWM to maintain a constant and perfect sine-wave output voltage to the user load. This is a cost effective load control solution.

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