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Steve

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I have measured 3 phase Irem rectifiers at anyplace from 8 to 12% ripple depending on size. When the relay board is working correctly inrush is always with in Osram specs. I've had many a relay board fail in these and it usually means to low of start voltage. I have seen single phase Irems measure quite a bit better than the three phase units. Typically at 6 to 8%.

Kneisley units are by far the cleanest I have measured and are typically at 4 to 5% for the three phase stuff. However the construction of them leaves alot to be desired. The rectifier stack though is about as bullet proof as they come.

Christies will typically measure as well or just slightly worse than the Kneisley's will. I always felt that Christies heatsinking was a joke though. A fan is definately necessary on these when running platter. What I really hate about Christies is the diodes they use. They are epoxy sealed instead of glass sealed and over a number of years the epoxy lets go from heat stress(yes, even with fans). You'll find that the diode has actually failed from mechanical failure as you can usually wiggle the stud itself around. Replacing these with glass sealed type diodes offers far higher reliability overall and less heat stress failure. Almost all diodes I have replaced in Christies over the years were from this sort of failure. Only a few shorted or open diodes have been observed.

As far as Strong switchers go they were alot of trouble back when they were new but after mechanical problems were straightend out in early units they proved in my locations to be no more or less reliable than iron core units. Over the last two years I'd say I've delt with an equal number of problems form iron core type and switchers. The new style smaller Strong switchers have been ultra reliable for us. We have several that get a constant beating on our rental Super Troupers. I've had one failure with the small switcher since they appeared on the market. This was about three weeks ago. The twist lock plug burnt up on one. This was due to compression set of the wires in the twist lock plug for the three phase. Checking all the twist locks in the plex revealed some others that were really loose as well. The rectifier was still ok though, just suffering a chared 3 phase connection socket. These switchers are also pretty much immune to line voltage fluctuations due to the regulation that is built in. we have had great luck in rural areas with them maintaining constant current on the lamps and they give great lamp life.

Overall I feel that rectifiers are like Jet planes. You have about the same chance with any of them but they all require proper maintainance and necessary upgrades to keep them reliable.
Mark @ GTS
www.getgts.com

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The biggest problem I have had with the Christie rectifiers are diode failures from ignition pulses. Unlike other rectifier manufacturers, there is nothing on a Christie rectifier after the diode stack to squash the noise pulse. Likewise, there is nothing on the input side to squash spikes coming in. Now they DO have capacitors and MOVs on a surge protection board (and one capacitor across the DC terminals on the old DC output terminals) but nothing right across the diode stack or the input terminals. We have found that placing a capacitor across the output stack pretty much stops the diode failures. I know Christie is working improving this.

Steve

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