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32a distro build

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snowflake View Drop Down
Old Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 24 July 2015 at 3:10pm
Hi

I've now got the distro pictured in the original post. it is configured as

16A MCB feeding 20A Powercon
16A MCB feeding 20A Powercon
16A MCB feeding 6*10A IEC
32A MCB feeding 2*20A Powercon

this isn't safe or optimal, is it?

should I change it to

20A MCB feeding 20A Powercon
20A MCB feeding 20A Powercon
20A MCB feeding 2*20A Powercon
10A MCB feeding  6*10A IEC

cheers
Phil
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adyk View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote adyk Quote  Post ReplyReply Direct Link To This Post Posted: 24 July 2015 at 3:33pm
are you sure its the same as that doesnt sound right?


Edited by adyk - 24 July 2015 at 3:35pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote shagnasty Quote  Post ReplyReply Direct Link To This Post Posted: 24 July 2015 at 9:44pm
Originally posted by snowflake snowflake wrote:

Hi

I've now got the distro pictured in the original post. it is configured as

16A MCB feeding 20A Powercon
16A MCB feeding 20A Powercon
16A MCB feeding 6*10A IEC
32A MCB feeding 2*20A Powercon

this isn't safe or optimal, is it?

should I change it to

20A MCB feeding 20A Powercon
20A MCB feeding 20A Powercon
20A MCB feeding 2*20A Powercon
10A MCB feeding  6*10A IEC

cheers
Phil
 
your version sounds better to me, but bear in mind that is 70A out against 32A in, I am not sure your load diversification factor should be that high!
 
If you intend running maps on the 10A make sure you use a c (even D) curve mcb on it....
 
 
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Old Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2019 at 1:27pm
I am using this distro in the following config but want to do some upgrade work:

AC32 RCD inlet
B16 MCB feeding 20A Powercon to SAE PQM13
B16 MCB feeding 20A Powercon to SAE PQM13
C20 MCB feeding 2*20A Powercon - one to DJ console/decks and second to 4gang extension
C10 MCB feeding  500W UPS which runs rest of rack and 6*10A IEC

amps say on the back 4650W @220V. I use one for left stack and one for right. so two channels bridged into sub (4R load). third channel into 4R kick. fourth channel into 32R mid/high. so neither amp should draw full rated power.

meter is a DHC3PB-VAZ

I am aware my power cables are a bit mickey-mouse. Although 32A connectors they are H05 2.5mm2 cable and 14m long (sometimes I have to daisy chain more than one cable too!). the distro has a captive lead which is long enough to use where power is convenient and short adapters to run of 16A and 13A supplies.

Pushed the levels a bit at carnival and got some peak current readings of over 50A so quickly turned back down. the meter display only updates about once per second though and I don't know what time period it averages the reading over.

1) should I swap the two B16 for for C16 (or D16) to run the amps off? Or would I be better running both amps off a C20 and having seperate supplies for DJ console and extension lead that might get other (non-audio) stuff plugged into it e.g. lights, chargers.

2) should I upgrade the RCD?

3) can someone suggest an alternative meter that will give me readings that actually tell me when I am approaching the point that the 32A protection will trip.

4) I've been okay so far because always made sure peak current is below 32A so average has been much lower. If I start pushing the average power nearer 32A what power cable should I upgrade to?


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Post Options Post Options   Thanks (1) Thanks(1)   Quote Danielr Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2019 at 9:29pm
Originally posted by snowflake snowflake wrote:

2) should I upgrade the RCD?
4) I've been okay so far because always made sure peak current is below 32A so average has been much lower. If I start pushing the average power nearer 32A what power cable should I upgrade to?
Assuming the RCD you have is adequate, why upgrade?

Cable ratings are reasonably simple the figure out...
The formula is current x distance / a constant that relates to the cable diameter and number of phases.
(he constant relates to amp meters per voltage drop.)
For single phase.
2.5mm = 128
4mm = 205
6mm = 306

So if you want 32a x 19 meters / 128 (as you currently use 2.5mm CSA) = 4.75% voltage drop.
you can look up that formula here:
https://www.metroid.net.au/engineering/calculate-voltage-drop/

then you'd apply any de-rating as necessary depending on how many cables you have bundled together, whether they are in ducting, or on cable trays etc.

(if you look at this link there is a calculator where you put in the power or amps, number of phases, voltage drop you're tolerating in your system, and length. - then gives you the CSA depending on the cable type for necessary de-ratings etc.)
http://www.doncastercables.com/technical-help/

That suggests 4mm for the distances currents that you want. (assuming h07 cable, in free air/perforated tray carrying it.) (that's a 2.9% voltage drop.)

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 4D Quote  Post ReplyReply Direct Link To This Post Posted: 17 August 2019 at 11:11am
Originally posted by snowflake snowflake wrote:

I am using this distro in the following config but want to do some upgrade work:

AC32 RCD inlet
B16 MCB feeding 20A Powercon to SAE PQM13
B16 MCB feeding 20A Powercon to SAE PQM13
C20 MCB feeding 2*20A Powercon - one to DJ console/decks and second to 4gang extension
C10 MCB feeding  500W UPS which runs rest of rack and 6*10A IEC

amps say on the back 4650W @220V. I use one for left stack and one for right. so two channels bridged into sub (4R load). third channel into 4R kick. fourth channel into 32R mid/high. so neither amp should draw full rated power.

meter is a DHC3PB-VAZ

I am aware my power cables are a bit mickey-mouse. Although 32A connectors they are H05 2.5mm2 cable and 14m long (sometimes I have to daisy chain more than one cable too!). the distro has a captive lead which is long enough to use where power is convenient and short adapters to run of 16A and 13A supplies.

Pushed the levels a bit at carnival and got some peak current readings of over 50A so quickly turned back down. the meter display only updates about once per second though and I don't know what time period it averages the reading over.

1) should I swap the two B16 for for C16 (or D16) to run the amps off? Or would I be better running both amps off a C20 and having seperate supplies for DJ console and extension lead that might get other (non-audio) stuff plugged into it e.g. lights, chargers.

2) should I upgrade the RCD?

3) can someone suggest an alternative meter that will give me readings that actually tell me when I am approaching the point that the 32A protection will trip.

4) I've been okay so far because always made sure peak current is below 32A so average has been much lower. If I start pushing the average power nearer 32A what power cable should I upgrade to?



Your 32A extensions need to be on 3x 6mm csa to be compliant 2.5 is for 16A
DMZ. "The bass was intense. Girls were literally running up to stand next to the subs"
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 17 August 2019 at 12:04pm
thanks for replies.

I'm going to buy a D16 breakers for each amp.

will get some 6mm2 cable and and some 16A ceeforms and swap the connectors from my current cables onto the new cable.

I was thinking of changing RCD to RCBO but having read other stuff realise this isn't necessary.

anyone got any views on current metering? could I modify it by taking a CT off the incomer, putting that through a rectifier and capactior to average the current, and then use my meter to measure that? could recalibrate it to a known current by putting multiple turns round the CT.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RoadRunnersDust Quote  Post ReplyReply Direct Link To This Post Posted: 25 October 2019 at 10:13am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 25 October 2019 at 10:37am
is there any upstream protection for the 32a rcd? Otherwise your maximum demand might exceed 32a
Kevin

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Post Options Post Options   Thanks (0) Thanks(0)   Quote RoadRunnersDust Quote  Post ReplyReply Direct Link To This Post Posted: 25 October 2019 at 11:22am
That would be inherent in the 32A ceeform inlet unless you’re planning to supply it with something that breaches the regs like an non-limited 63>32 adapter

Given that any supply of 32A or less is supposed to now have 30:30 RCD protection it wouldn’t be unreasonable to have an appropriate defeat switch on the inlet RCD for connecting to an already protected supply to maintain discrimination 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 25 October 2019 at 11:53am
Originally posted by RoadRunnersDust RoadRunnersDust wrote:

That would be inherent in the 32A ceeform inlet unless you’re planning to supply it with something that breaches the regs like an non-limited 63>32 adapter

Given that any supply of 32A or less is supposed to now have 30:30 RCD protection it wouldn’t be unreasonable to have an appropriate defeat switch on the inlet RCD for connecting to an already protected supply to maintain discrimination 


wouldn't discrimination principle say that the outlet RCD protects the cable against damage, and the RCD in my distro protects against fault or over-current in my rack?

should my distro RCD be 32A type A rather than type AC?

should I downrate it to 30A so that overcurrent always trips the protection in the rack rather than the RCD on the outlet at the other end?


Edited by snowflake - 25 October 2019 at 12:02pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RoadRunnersDust Quote  Post ReplyReply Direct Link To This Post Posted: 25 October 2019 at 12:50pm
No, if they’re both 30mA/30mS (which they have to be for 32A or less) then whichever one is the most sensitive will trip if the fault is down stream of them both, which can be entirely random and totally against the point of discrimination. This is why you can get RCDs with variable threshold for further upstream of the distribution network.

RCD type/class is something entirely different. It determines things like DC sensitivity, etc.

You need to research the difference between an MCB, an RCD and an RCBO. An RCD has no over-current protection, the current rating on an RCD is just the amount of current it is rated to carry in normal use/how much current it is rated to break. The 30mA 30mS part is the threshold for how much leakage current will make it trip.

An RCBO incorporates RCD protection with the over-current protection of an MCB.

Depending on the curve characteristic and the physical state of the breaker on the supply you are using, a 32A MCB/RCBO could still trip sooner than a 30A MCB/RCBO. Through age, use and abuse (and intentional recalibration) the thresholds can vary a reasonable amount.

Without meaning to be rude, if you need to ask questions like this then you really shouldn’t be having a stab at DIYing it with advice from random people off the internet. I would strongly recommend you get someone with the appropriate skills/knowledge to spec/build/test it for you
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