Abstract
M.Ing.
With the enormous technological development that. is going on in the world, industries are
urged to keep up by either upgrading or replacing their existing equipment.
The existing diode rectifiers in Spoornet are being used in over 500 substations country wide
with definite success. The rectifiers are being expose to severe conditions, but have proofed
it self as robust and reliable over the past years. Thyristor rectifiers on the other hand may
be used as an alternative to the more usual diode rectifiers in 3kV DC traction substations.
With the benefits of the thyristor rectifier, there are some disadvantages associated such as
increased 12R losses, difficulties in load sharing between substations and harmonic distortion.
In the investigation to follow both the diode and controlled rectifier configurations will be
looked at to prove the feasibility of both during the study. The investigation will take the form
of simulation models by making use of the simulation program E.M TP. ('Electromagnetic
Transient Program). From the simulations it will be possible to get the voltage and current
harmonic distortions as well as the waveforms on any point of the circuit. A financial study
in the form of present replacement cost will also form part of the final conclusion.