We're arranging a music event where we're going to drive a few speakers and a dj controller. We've been trying to find a generator that would work and so far we only have access to three. All three generators are of the classic kind, they do not have inverters. The output is connected directly to the alternator.

The most likely candidate right now is a Honda ECMT 7000. It has an RMS of 6500 in triplephase which is more than enough for us.

Our issue is interference and voltage spikes. We're afraid that the generator could spike and break our equipment that will be connected through a power central 220v that converts triplephase to singlephase.

I've tried to search the web for an answer and everybody says different things. Half of the posts I see say it's fine and they've been doing it for years while the second half says it'll definitely fry the electronics.

What do you guys think? More specs on the generators and audio can be sent on request. The power is not an issue, we already know that. We're worried about the spikes.

Would the fuses in the central and some standard EU socket voltage protectors be fine?

  • \$\begingroup\$ Can you link specs for the "power central 220v that converts triplephase to singlephase" device? \$\endgroup\$ – Glenn W9IQ Jul 10 '17 at 16:13
  • \$\begingroup\$ @GlennW9IQ Probably something similar to this one: images.biltema.com/PAXToImageService.svc/article/xlarge/44727. Although it "converts" 220 V three phase line-neutral voltage to single phase 220 V line-neutral voltage. \$\endgroup\$ – winny Jul 10 '17 at 17:19
  • \$\begingroup\$ This "spike will kill your equipment" is nonsense. I've done so many concerts and forest parties I've lost count. What you should be concerned about in that very situation is if you have a ridiculously long three phase cable and strong single phase load, like incandescent lights on one phase and the two other being light or unloaded. Then the voltage drop on your neutral will increase the line-neutral voltage on your two other phases. "More light on the stage please!" Meter showing 280 V on the outboard already "No, we'll burn the FOH mixer!" Only 0.1 % of the population understood why. \$\endgroup\$ – winny Jul 10 '17 at 17:23
  • \$\begingroup\$ Thanks but I was looking for technical info, not just a picture of the converter. That doesn't look like a converter - more like a breakout panel. \$\endgroup\$ – Glenn W9IQ Jul 10 '17 at 17:29
  • \$\begingroup\$ @Glenn It is a breakout panel. The beauty of three phase with neutral. \$\endgroup\$ – winny Jul 10 '17 at 17:55

The times when a conventional generator output voltage or frequency could become unstable is during startup, shutdown, and when it is running out of fuel and starving. Always unplug during these conditions. A well maintained generator will otherwise be a reliable energy source for your electronics.

To keep the voltage in spec, always try to balance the loads between the three phases. If you get them substantially unbalanced, the advantage of the three phases sharing a common wire is lost - particularly with a longer three phase cable. This can result in one or more phases having an improper voltage.

  • \$\begingroup\$ So you don't believe there will be much if any issues with a conventional generator if we keep the load on all phases steady and don't put too much load on the generator? \$\endgroup\$ – arebokert Jul 11 '17 at 9:18
  • \$\begingroup\$ Just follow the tips in my answer and you should be good. Surge suppressors can give you some added assurance. \$\endgroup\$ – Glenn W9IQ Jul 11 '17 at 21:38

This is not a complete answer but should clarify your terminology:

We're afraid that the generator could spike and break our equipment that will be connected through a power central 220v that converts triplephase to singlephase.

The box doesn't convert anything. It just makes one phase available on each of the blue sockets simply by wiring.

enter image description here

Figure 1. Three-phase breakout box.


simulate this circuit – Schematic created using CircuitLab

Figure 2. Breakout box internal wiring. (CircuitLab seems to be struggling with the wire crossings. Connections are marked with dots.)

The breakout box has no active components inside. It just takes 3-phase L1, L2, L3 and N (and Earth) input - note the pins rather than sockets - and "breaks them out" into two more 3-phase sockets (red) and four (two shown) single-phase sockets (blue). I have not shown the circuit breakers on the schematic.

  • \$\begingroup\$ That does explain everything a bit further. I was not aware that the distribution board was just a "splitting" of the three phases, I thought there were some conversion going on. \$\endgroup\$ – arebokert Jul 11 '17 at 9:17

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