MrVerylongusername
1252 posts
Sep 27, 2010
1:00 PM
|
Not harmonica related, but I'm hoping there's a knowledgeable sparky in the house because it does relate to gigging.
My band has been booked for a wedding next year. We visited the venue and were told by the manager that they used 3 phase electricity and bands usually had problems because of this. However she also said there was no room for a band, when clearly there was.
We got a strong feeling that they were just trying to discourage us from playing, because they want their in-house DJ to play (and charge the couple extra for that 'privilege'). To me the whole 3 phase thing sound like b.s.
Surely at the consumer end it makes no difference how the electricity is delivered?
Given that we've already taken a deposit and signed a contract with the bride and groom to be, is there anything other than the manager's attitude that we should be concerned about?
|
The7thDave
168 posts
Sep 27, 2010
1:36 PM
|
They might have some 3-phase for larger items of equipment (A/C, water pump, etc.), but you can't run lights or small appliances off 3-phase. So if they have lighting fixtures, then they have at least one single-phase circuit there.
----------
--Dave
--------------------
* BTMFH *
--------------------
Last Edited by on Sep 27, 2010 1:43 PM
|
MrVerylongusername
1255 posts
Sep 27, 2010
2:32 PM
|
Thanks - I thought so.
Either the manager doesn't know what she's talking about, or she's trying to discourage us, or my bet - a bit of both.
|
Preston
564 posts
Sep 30, 2010
5:42 AM
|
In three phase power, one nuetral can be used to serve 3 single phase branch circuits. When this happens, the nuetral carries only the unbalanced load.
For example, if was a true single phase circuit, (one phase conductor and one nuetral)and there was a 10 amp load plugged in, you would read 10 amps across both the phase conductor (I'll call it the hot from here on out) and the nuetral wires. However, this not the case if it is part of a 3-phase multi-branch circuit (where there are two or three hots sharing a nuetral). Say one receptacle has 10 amps and the other has a 5 amp load, then the amperage across the nuetral is only 5 amps, or the difference if you will.
Power coming out of the receptacle is alternating current, or AC, and most of electronic equipment is powered by Direct Current, or DC. There are small converters built into electronic equipment that makes the switch between AC to DC. Unfortunately, these converters screw up the waves of the AC and cause "Harmonics".
AC cycles 60 times per second, or 60HZ. Harmonics cylce back to the power source in revers at 120, 180, etc, etc HZ. Unfortunately, the very equipment that creats these harmonics, are also greatly affected by them. Among other serious problems, it can cause a "Buzzing" in not only the equipment, but the electrical system itself.
If you refer back up to the top of my explanation about 3-phase, you can see that plugging in an amp to the receptacle of one circuit, can screw up a keyboard plugged into the receptacle of another circuit because of the shared nuetral. And so on and so forth.
My guess would be they have other equipment plugged in that is already causing the harmonics on their electrical system, and when the band plugs in, their shit starts humming. I've heard of some converters that have safeties on them that would even shut them selves down in the event of dirty power caused by harmonics to prevent damage.
|
MrVerylongusername
1258 posts
Sep 30, 2010
6:40 AM
|
Ah...
Thanks Preston. As I'm not technical when it comes to elctricity, can you clarify that I've got this right:
1) there is a potential risk to our equipment from voltage spikes.
2) There is a potential sound problem - is it similar to a ground loop hum in a single-phase system?
3) We may trip a circuit breaker.
Can you suggest anything we could do to minimise these problems/risks? I am starting to get very uncomfortable about this gig and we may have to return their deposit and decline the booking - which I really don't want to do.
|
Greg Heumann
799 posts
Sep 30, 2010
10:09 PM
|
@Preston
Wouldn't it be unusual for 3-phase wiring to be used to power 110V sockets/ I always thought 3 phase was for high power 220V motors and was usually on a completely separate circuit from the 110V runs - but this is not my area of expertise.....
----------
/Greg
|
rharley5652
238 posts
Sep 30, 2010
11:19 PM
|
@ MrVerylongusername
Three phase electricity powers large industrial loads more efficiently than single-phase electricity. When single-phase electricity is needed, It is available between any two phases of a three-phase system, or in some systems , between one of the phases and ground. By the use of three conductors a 3 phase system can provide 173% more power than the two conductors of a single-phase system. Three-phase power allows heavy duty industrial equipment to operate more smoothly and efficiently. 3 phase power can be transmitted over long distances with smaller conductor size.
Given that we've already taken a deposit and signed a contract with the bride and groom to be, is there anything other than the manager's attitude that we should be concerned about?
Yes ,.
make sure your plugged into single-phase Outlets !!
----------
Simply Unique Kustom Mic's By Rharley
|
Preston
565 posts
Oct 01, 2010
9:49 AM
|
Greg,
It looks like rharley answered your question. 3 phase power is brought into the building and split into single phase branch circuits at the electrical panel. Quite often 3 receptacle circuits will share a single neutral, compounding the problem of harmonics.
|
oldwailer
1365 posts
Oct 01, 2010
10:10 AM
|
I think I'd just plug in an old amp and see what the problem is--before the gig. This is a test that would need to be done at a time when business is at the same level as the gig--since a random machine kicking in right in the middle of your drop dead solo could screw things up.
The really obvious solution is to get a couple of those power supply thingies--the one I have lets me play for as long as I can stand it--then you wouldn't be attached to the power grid--and you're good to go on the street as well. . .
----------
|
rharley5652
239 posts
Oct 01, 2010
1:44 PM
|
Just take a circuit tester or an Electrician Buddie with ya ,. an check out an outlet,.your reading should be 110V here in the States,..They may not have run single phase into the place,..YA don't want to plug anything into their outlet without checking first.
Next best bet if ya don't want to cancel the the gig sense ya already taken a deposit and signed a contract with the bride and groom to be,
Bring in your own Gas generator,.set it up out back of the place,..run ya cords inside ,.an play the night away,..
Good luck
----------
Simply Unique Kustom Mic's By Rharley
|
