ELC / Protection Relay

Electronic Load Controller (ELC) / Protection Relay/ Induction Generator Controller (IGC)


This site has moved to www.hydroelectronics.net

Controllers are available for order on the new site.

Features for the user

Flexible - works for a wide range of installations
Easy adjustment on site due to microcontroller technology

Technical specifications

  • Voltage nominal:  220 - 240V
  • Frequency:  50/60 Hz
  • Power: from micro scale (few 100 watts) to medium scale (megawatts)
  • Phase: 1 or 3 phase
  • Generator: Induction generator (asynchronous) or synchronous generator

Metering on the display:

  • AC Mains Voltages
  • Frequency
Optional:
  • DC Voltage
  • Hour counter
  • Ampere meters

Protection features

  • Over/under frequency
  • Over/under voltage
Optional:
  • Overcurrent

 

Features for the engineer

- Simple to build, simple to use, simple to repair
- Standard components -> cheap
- Flexible: from micro scale (few 100 watts) to medium scale (megawatts)
- customizable: simply change the software to add features and behaviour
- In circuit serial programming ICSP
- if you dont like to build it yourself, just order it here

Open Source 

under GPL:
All software and hardware can be modified and commercially used.
Only conditions:
  1. you must keep your hardware and software modifications open-source and published online
  2. you must mention all contributors


Principle

Different operating principles of ELCs
Every ELC/IGC basically continually adds or removes ballast load (dump load).

Problem is, how to achieve a truly continuous load change?
  • You can use phase angle switching, but this introduces harmonic noise, and it is not trivial to switch high currents (triacs have a limited current change rate I/dT and need isolated heat sinks)
  • To avoid this, you can switch dump loads as a whole, but then you need different sizes of them, and they need to be well defined in their sizes to reach a halfway decent continous spectrum -> part sourcing and installation becomes complicated and regulation is not very precise.

Solution:
Zero crossing switching - no harmonics, no complicated setup, but still decent continuous load change
The dumploads are switched on one after the other.
If only part of a certain dump load is needed, it is switched on for only a number of 50Hz half-cycles.
Specifically, a base of 10 Half-cycles (= 5 full cycles = 100 ms = 10Hz) is used. So any dumplod can be regulated in 10% steps.
10Hz is well above the reaction time of even small systems due to their mechanical inertia, so there shouldn't be any oscillation problems.

Dumpload at 40%:


- Hardware
      - schematics
      - PCB
      - BOM
- Software

- history

FAQ

Why not use an AVR microcontroller, programmed with Arduino?

In hindsight, this would have been the more open source approach, and the way to go.
However, I was inspired to use a microcontroller by Manfred Mornhinweg's project, and he used a PicMicro. And PicMicro MCUs are certainly very well suited for our purposes.

The original idea to build an ELC came from Jan Portegijs.
I built two 3 phase versions of these, one of them with extended modifications, and they worked. But one of them got fried, probably due to overvoltage. (That's why you should use an overvoltage protection) That's when I realized they are impractical, because nobody can repair them within reasonable effort, except the one who has built them, due to their complexity.
For example you will need an oscilloscope to diagnose the function of circuits.
That's when the idea of a much more modular system with readily available components was born.

Other interesting reading

Integrated Electronic Load Controller with T-Connected Transformer for Isolated Asynchronous Generator

Electronic Load Controller for a Parallel Operated Isolated Asynchronous Generator Feeding Various Loads

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