Just a thought, do we have load balancer, but for power?

[Chiyawa]

Hi,

 

I'm thinking of getting a 3 phase power for my workshop, and I just wondering, is there a device to balance the load between the power phases? I try to minimised my kVAr as much as possible, and this actually struck me. We have load balancer for networks, but do we have load balancer for power?

 

Regards,

Chiyawa

[suedseefrucht]

2 hours ago, Chiyawa said:

balance the load between the power phases? I try to minimised my kVAr as much as possible

You don't need to worry about balancing loads if you are not a very big company.
The main problem at the workshop will be the current fuse.
If too many devices are drawing current from 1 fuse, it will cut the power.

So you should spread the devices to multiple current fuses and to multiple phases, because there is a current limit for a single phase too.

[greenhorn]

As @suedseefruchtalready said, load balancing can be done, but this only really makes sense at a much larger scale. At a home/small company/workshop level, the "balancing" is usually done in a static way by the electrician who should determine which single-phase circuit to attach to which phase so that it becomes less likely that one will blow the fuse of a single phase while still drawing reasonable amounts of current/power.
You will also find that more power-hungry devices tend to need a 3-phase connection themselves. In that case, you can hope the device's manufacturer has done some internal balancing inside of that device.

Since you are talking about kVAr, I am wondering if the thing you are actually more concerned about is the power factor. Devices with a bad power factor can be a problem (usually from the workshop-level of power consumption upwards), but in many cases the device manufacturer uses a power factor correction mechanism to minimize that problem.

It would be helpful if you could describe your setup a bit more (number and type of device, current/voltage rating, power factor, type of mains supply with max allowed current draw per phase) in order for us to figure out what advice we can give you.

[Chiyawa]

1 hour ago, suedseefrucht said:

*Snip

I see.

49 minutes ago, greenhorn said:

*Snip

I see. Well, currently, this workshop doesn't have a lot of stuff.

 

We have 5 computers,

4 units of milling machine with something like this (rated power is 2.5kW, pf 0.95 according to the lable):

2 units of cutting tools (circular saw, 3500rpm, about 30cm diameter circular saw blade). Not sure how much power they draw, though.

And a compressor with 5hp motor.

 

We also have 6 air-conds as well, all of them are rated 1.5hp, standard household one. And also some lightings and exhaust fan as well.

 

I plan to buy an automated milling machine such as this (https://www.hcnc-group.com/cnc-machine/cnc-milling-machines/cnc-metal-milling-machine.html?gclid=CjwKCAiAo4OQBhBBEiwA5KWu_3ARL-xPJVSCRRqspOpK3SZqiioy5Z9X_qKWOM0NwGIMx0Ep08IZ3RoCeGMQAvD_BwE) in the future (not the exact model, but something similar, an old recond one). The sales consultant advise me to install 3 phase power because the machine requires 3 phase power to operate.

 

Oh, we're mostly on metal works. We sometimes do wood works.

[greenhorn]

Ok, that is quite a large setup. I think the best thing would be to get an electrician who then designs the layout of your electrical system and also determines what kind of connection you need from your energy supplier. Given the type and amount of devices you have/want to have, 3 phase power definitively makes sense from a physics point of view and is probably even mandatory for the expected power draw.
One thing to consider will also be which devices will/can be active at the same time, because that influences the peak power consumption the system has to be designed for.

[Chiyawa]

11 hours ago, greenhorn said:

Ok, that is quite a large setup. I think the best thing would be to get an electrician who then designs the layout of your electrical system and also determines what kind of connection you need from your energy supplier. Given the type and amount of devices you have/want to have, 3 phase power definitively makes sense from a physics point of view and is probably even mandatory for the expected power draw.
One thing to consider will also be which devices will/can be active at the same time, because that influences the peak power consumption the system has to be designed for.

Indeed. But that means I might have to rewire everything which will add more cost. But thanks anyway. I thought if we have like a device which take 3 phase and then convert to a single phase, then we don't really have to do a lot of wiring.

[greenhorn]

4 hours ago, Chiyawa said:

Indeed. But that means I might have to rewire everything which will add more cost. But thanks anyway. I thought if we have like a device which take 3 phase and then convert to a single phase, then we don't really have to do a lot of wiring.

In theory, this is possible, but not worth it (due to cost and power losses). You also have to take into account that those devices usually need a lot of power, which means that a single phase circuit would need to handle a lot of current.
If you have to rewire everything, keep in mind that there might be several ways of doing that depending on what the electrical code in your country specifies. Since this is a workshop, you could think about installing wall-mounted or ceiling-mounted conduits for the wires, which should be easier and less expensive than running everything inside the walls.

[Chiyawa]

28 minutes ago, greenhorn said:

*Snip

Indeed. Well, looks like I need to shell a bit more, but I think we're in good timing as well because we really need a little overhaul of our electrical wiring. Thanks.

 

Although, I wish that this load balancer will be a thing because we can balance out the phases so we can minimised the chances of overloading a phase, but I guess that in theory this is hard to achieve. As electricity tariff gets more and more expensive, waste is pretty much an issue if we couldn't minimised it.

[greenhorn]

49 minutes ago, Chiyawa said:

Although, I wish that this load balancer will be a thing because we can balance out the phases so we can minimised the chances of overloading a phase, but I guess that in theory this is hard to achieve. As electricity tariff gets more and more expensive, waste is pretty much an issue if we couldn't minimised it.

Since you will know the data of your more power-hungry devices, you can look at their rated power and derive their current draw. Also keep in mind that some devices can have very large inrush currents (which sometimes can trip a breaker, so make sure the proper type of breaker is installed). What you could do is to ask the electrician to install current monitors for each phase so you know how close you are to overloading a phase.
Depending on the needed current rating, there should be resettable circuit breakers available. This makes sure that the downtime is minimized in case a breaker trips. I'm not sure how far "up" the resettable ones get in terms of nominal current.

[Dutch_Master]

IMO you have a fundamental lack of knowledge how energy distribution systems work, in particular electricity, so the aforementioned electrician is a well founded advice I'd underwrite. I also concur with the need to rewire your shop, especially as it has to be done for the new equipment anyway. Get an electrical engineer involved, (s)he can make the required calculations and designs to load-balance your equipment properly.

23 hours ago, greenhorn said:

power factor correction mechanism

There's nothing mechanical about it, it's either a capacitor or inductor (capacitor for inductive loads, inductor for capacitive loads)

[greenhorn]

2 minutes ago, Dutch_Master said:

There's nothing mechanical about it, it's either a capacitor or inductor (capacitor for inductive loads, inductor for capacitive loads)

I know, just an expression. I am aware that it is usually a capacitor or capacitor bank in most cases. I have also seen such a thing in combination with LC filters on one PCB.