multiple servo in electrical enclosure

[damunk]

How would one go about wiring 4 to 6 servo drives each rated 10A and peak current 30A each.

It is single phase 240V.

Would you go the route of either;

1) MCB ; magnetic contactor; bus bars and two feeds of 40A = 80A from distribution board

2) Just put a standard UK 3 pin plug on them with a 13A fuse in each

or

3) DIN fuse board instead of MCB's, magnetic contactor; bus bars and two feeds of 40A = 80A from distribution board


Canyou help me because I would like to finish the design of the electrical enclosure before presenting to electrician to show him that I have some sort of clue what i'm talking about haha.

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[Al_The_Man]

For a start, running each off of a separate outlet is a really bad idea, you need to set up a proper industrial enclosure with the correct power supply feed with suitable capacity.
The entry to the enclosure would first be the disconnect followed by suitable fusing for each servo amplifier and power device etc.
There is a copy of Industrial enclosure wiring etc, AKA NFPA79 out there in PDF to get some idea, it is NA based, but most will apply to a UK application.

[damunk]

How come in my manual for a 3 phase setup it shows a diagram of a mcb, emi line filter followed by a magnetic contactor where as a single phase setup people are recommending a fuse style setup;(i.e din fuse holder boards etc)

[Al_The_Man]

For 1ph you should also have a isolation disconnect on the enclosure this can be followed by suitable circuit fusing, a magnetic contactor should be included for the E-stop condition/circuit.
Generally the E-stop would control all motive power and critical output circuits, control display and generally input devices can be kept live.

[damunk]

like these

[Al_The_Man]

Quite a fancy one I am not familiar with, but according to the specs should work.
Incidentally although I got my training in the UK , I have been absent for some decades, so am not up to date on the latest EU available components.

[Jim Dawson]

Here is how I did mine. The power distribution block is fed by a 50 amp breaker.

Each contactor is fed by a 30 amp breaker

[damunk]

Here is how I did mine. The power distribution block is fed by a 50 amp breaker.

Each contactor is fed by a 30 amp breaker

Thank you so much Jim.

Also Jim. I’ve noticed a lot of modern constructions are now changing from mcb to the fuse type din holders as per picture I posted.

Is this because the mcb can “spark” “big shock bang”
Where the fuse type there is no light flash , silent blow”

?? We have industrial machines that use heater bands to warm up extruder screws and they now have changed from mcb to fuse din holder type.

Edit: maybe the fuse blows at the current states where a mcb is not as efficient and can allow overload or a time delay before it pops. I wonder which is more suited to a servo drive .

[Jim Dawson]

I am not up to speed on current fuse technology. It could be that the new style fuses are designed to prevent arc-flash injuries. I'm not really sure.

I normally just use C curve breakers as MCBs on servo drives, they will trip to prevent wiring overheating and possible resulting fire. No circuit breaker is going to save the servo drive if something goes horribly wrong. On the other hand, modern servo drives and VFDs do a great job of protecting themselves from failures on the motor side.

[damunk]

Jim,is yours wired three phase as mine would be single phase.

[damunk]

just noticed your mcb's looking like single phase mcb

[Jim Dawson]

Yes, that is a 3 phase panel for my lathe. But there is little difference when wiring single phase.

Here is a similar panel I did for a single phase system, using 2 pole breakers rather than the 3 pole breakers used in the 3 phase system.



And another panel I will be starting on tomorrow, also single phase.

[damunk]

did you use threephase contactors on the singlephase panel?

how did you wire them?

just live and neutral ; is the third pole auxliary for a pilot light?

[Jim Dawson]

Yes, I only used 2 of the 3 poles. You could use the 3rd pole for anything you wanted, a pilot light if desired. I guess for single phase you could use PRD relays, but I have never seen those in a DIN rail mount, and I prefer to use 35mm DIN rail for mounting stuff in a panel.

Something like this https://www.amazon.com/TE-CONNECTIVI...l%2C128&sr=1-2

[Al_The_Man]

did you use threephase contactors on the singlephase panel?

how did you wire them?

just live and neutral ; is the third pole auxliary for a pilot light?

If feeding non-motor loads with the contactors you most likely can use them for three separate loads, e.g. three drive unit/supplies, it is not normal to switch the neutral., i.e. live conductors only.
This method particularly if the loads/contactors are also enabled by the E-Stop.
Normally you would draw up a schematic, this then enables wires to be numbered for labeling and future identification.
I imagine that the UK has a NFPA79 equivalent for wire colour codes etc, I don't recall what we used, it has been a while, The wire gauge in imperial when I left!!

[mactec54]

How come in my manual for a 3 phase setup it shows a diagram of a mcb, emi line filter followed by a magnetic contactor where as a single phase setup people are recommending a fuse style setup;(i.e din fuse holder boards etc)

AI is correct, the power entry to the cabinet you need to have a Safety disconnect, then a MCCB for the max load you are going to switch, Then EMI Power Filter from there you can use a separate SSR for each servo Drive, or you can of cause use ((1) Contactor to turn off all Drives, if you use a Contactor make sure it has a snubber in place.

You can only use (1) Power source, to supply Power to your Cabinet, or you will have a Ground loop problem

Fuses are a thing of the past, for 240v wiring, you use MCCB wherever you want for this type of install, some low voltage power supplies have fuses inside, but these too can use MCCBs also for the 240v supply.

[mactec54]

Thank you so much Jim.

Also Jim. I’ve noticed a lot of modern constructions are now changing from mcb to the fuse type din holders as per picture I posted.

Is this because the mcb can “spark” “big shock bang”
Where the fuse type there is no light flash , silent blow”

?? We have industrial machines that use heater bands to warm up extruder screws and they now have changed from mcb to fuse din holder type.

Edit: maybe the fuse blows at the current states where a mcb is not as efficient and can allow overload or a time delay before it pops. I wonder which is more suited to a servo drive .

MCCB is more efferent than a fuses, will ever be, especially industrial quality, if they have changed to fuses then it's because they can make more sales, fuses can be expensive for inductive loads like heater bands Etc.

[damunk]

MCCB is more efferent than a fuses, will ever be, especially industrial quality, if they have changed to fuses then it's because they can make more sales, fuses can be expensive for inductive loads like heater bands Etc.

from google;

The SSR is a semiconductor switch. It provides a higher precision control than contactors. ... This high frequency switching feature provides higher precision control. (2) It produces almost no electronic noise (e.g., EMI) because the power is switched on and off when AC voltage is at the zero level.

Why more people not use ssr? ssr more suited to a servo drive?

so basically; 1) main power in; on/off knob with MCB for just main power(80amp or what ever is required) 2) 1 of line filter to 4 SSR's to each servo.

as simple as that? instead of messing about with mcb and contactors for each servo. would save alot of space i suppose. but i thought that each servo would require a suitable mcb just incase one screwed up and tripped so you'de know which one is screwed up.

[joeavaerage]

Hi,
SSR's have been developing and the prices have come down while performance has gone up and would be a good alternative to contactors.

There is one issue that Matec has raised eleswhere is that SSR's all have a little leakage current, if you buy quality SSR's not usually a problem, but I would not rely on an SSR
of any description to isolate a circuit so you could work on it. A genuine isolating switch or contactor is safer.

Craig

[Al_The_Man]

SSR's are not typically used in power supply applications, they can fail closed and defeat E-Stop conditions etc, as an example.
Also they do not generally conform to local regs.
As I posted, I would use 3ph contactors for the control power of 3 1ph devices.