Power supply wiring

P

Pyjamas

New elf
Joined
Apr 27, 2021
Messages
25
Hey everyone,
Just wanting some advice. I'm designing a 3d printable power supply box to have a bank of four LRS-350-12 PSUs inside. I'm trying to work our the position of wire clips, cable glands and channels depending on what's appropriate for wiring. Can the four PSUs be wired as per the diagram? Or do the active wires need to feed each individually via a terminal block?

Cheers!
Paul
Power supply box.jpg
 
It is fine to wire as is in principle.
One thing to consider is inrush current at switch on however. Some people have had problems where the circuit breaker to the house is tripped at switch on.
Also look at the total power of each supply to make sure it does not overload your circuit. Even though most power points are 10 amps, a lot of cables are rated less so make sure you power it with adequate wiring.
 
@Johnnyboy do you have a link or listing for the yellow fork connectors used on your PSUs? I have a 2nd set on order hoping they are slim enough to fit as the last lot I got were 1.5mm too wide (outer width, inner is fine for the screw terminals)
 
djgra79 said:
@Johnnyboy do you have a link or listing for the yellow fork connectors used on your PSUs? I have a 2nd set on order hoping they are slim enough to fit as the last lot I got were 1.5mm too wide (outer width, inner is fine for the screw terminals)
Click to expand...
They yellow ones I got from jaycar like the link @Adsy gave. Quite expensive and should have got from AliExpress but I was in a rush. The rest were AliExpress as I wanted mostly correct 240v colours (couldn’t find brown, so used red)
 
Skymaster said:
Usually the colours dictate the wire size - did you find them all to be the same diameter for the wire side?
Click to expand...
I managed to find a seller that could produce any diameter in any colour. The ones I’m using are all the same size, just different colours.
Overkill as usual on my behalf lol
 
Skymaster said:
Further to the above, the LRS350 has a rated typical input current of 3.4A. So you should not put more than three on a single 10A feed line.

The LRS600 is rated at 7.5A typical on the AC side at 240V so they should technically be all individually cabled.
Click to expand...
Sorry I’m a bit confused by the LRS600 comment. When you say they should be individually cabled, are you saying from the PowerPoint, there should be an extension lead to each power supply? But if there are 2 extension leads coming from the same double PowerPoint, wouldn’t that exceed the 10am rating for the PowerPoint, so would trip the fuse at the switchboard?
 
(Note, the following contains Australia specific info)

The 10A limit is for the plug and socket. For a double power point that gives 20A (10A on each). Having said that, it would be typical for a house to have a 16A breaker on each power circuit, so I guess technically with LRS600, with one lead going to each power point, you'd be pretty close to the limit when both power supplies are running flat out (7.5A + 7.5A = 15A of 16A allowed by the breaker).

The 7.5A will be due to a combination of the power supply efficiency (~90% according to the datasheet), and crappy power factor (0.4 to 0.6 according to https://www.meanwell.co.uk/knowledge-base/what-is-pfc).

The RSP series power supplies include power factor correction and as a result have much lower ratings for the AC current. Having said that, LRS seems to be the most popular choice in the hobby.

If you're designing your show to handle white at 100% brightness, you'll run into these limits much sooner that when you'll actually hit these limits (i.e. you're unlikely to be running a show at full brightness, and it's unlikely to be all white).
Another note, the Mean Well datasheets talk about 230V. I don't think I've ever seen a voltage that low here. Typically at my location I'll get 243 to 250V, which would reduce the current further.

If you're interested to learn more about power factor (relevant to the AC side only) there are multitudes of resources on the Internet, however this site has a specific table mentioning power factor and the influence it has on cable size: https://mepacademy.com/power-factor/
 
Also, looping back into the original post and mention of 3d printing, I saved myself some time and paid for these STLs: https://inspirelightshows.com/product/meanwell-lrs-350-mounting-rack-stl/
I used the 3x stacker for my main control box, and the 2x stacker for a couple of remote power boxes.

I modified the STLs to support a SONOFF POW remote switch so I can both monitor power usage, and turn of power to the pixels out of show hours. Mounted in CG1500 enclosures I picked up a few years back now. With the single supply I didn't seem to need any ventilation, I'll likely add something in when expanding to the second supply.

itead.cc

SONOFF POW Elite Smart Power Meter Switch

【LCD Screen】Track of power, current, voltage, and cumulative power consumption of your appliances in real-time on the LCD screen. 【20A Max Load】Support maximum 20A load, POW Elite compatible with m…
itead.cc itead.cc
<--- if you want to control via MQTT and not be linked to the SONOFF cloud
photos.google.com

2 new photos · Nov 20, 2022âââAug 21, 2023 ð¸

Tap to view!
photos.google.com photos.google.com
 
Last edited:
Thanks for sending me down a rabbit hole.

LRS-600-12
RSP-500-12
LRS-350-12
RSP-320-12

Now, let's not get into 5V where we hit the DC current limits before the power limits....
 
Last edited:
Katekate said:
those spec sheet figures seem wrong. 7.5A at 240v is 1800W
Click to expand...
Thanks @Kent for explaining it out.
"What he said" 🤣
The data sheet should always be the source of truth.


On the 230V / 240V comment,-- there has been harmonization between 220 V and 240V countries since the 80s in various IEC etc standards.
In around 2000, Australia(**1) switched from a nominal 240 to 230V, as the UK had done. Europe moved from 220V to 230V as well.

Previously the tolerance at customer point of supply was specified as 240V +/-6%, which gives a range of 225V to 254V
It's now 230V +10/-6% which gives a range of 216 to 253V

So in essence the acceptable range is still roughly the same. (This also brings nominal 3 phase to 400V, not 415V).

Now, the reason why you don't see the voltage change is that the generation facilities still generate at 240V(**2). As this is still within the tolerances of the new range, there hasn't been a need to physically change anything.

Notes:
**1 - all states except for WA and Qld. Queensland are in the process of adopting 230V as the standard.
**2 - I'm aware that generation and distribution is done at much higher voltages and stepped to low voltage at the pole/pad transformer, but this is irrelevant for this discussion 😁
 
Last edited:
You must log in or register to reply here.
Back
Top