Load Schedule

[SUD]

Please help me estimating load for an industrial socket 16A, 32A and 63A as i saw certain schedules in which it was shows 63A as getting 39000Watts per phase and in another loasd schedule drawing it shows 13000Watts per phase i mean whats the strategy in estimating this load??? Am a trainee any help would be helpful  Thanks The suppllied voltages here are 230V 1phase and 440V 3 Phase 50 hertz system.

 

[phil d]

Working out loads is necessary to ensure you have enough power to run what you are intending to run, if you were designing a system with no idea of the actual load, then you'd take it as stated load, so if you had 3, 16 amp sockets then you'd take the maximum load as 3x16=48 amps. Then if you had say a 32 amp socket also the potential load would increase to 48+32=80 amps, so if you had an 80 amp supply then you can see that potentially you could be up to your maximum available load, and you haven't even factored in say lighting or small sockets.

However in a situation where you know the load it can be easier, lets imagine you still have the same number and type of sockets, but you know the load to be taken, imagine the 16 amp sockets are still carrying 16 amps, but the appliance connected to the 32 amp socket is only using 20 amps, you know have a saving of 12 amps, which could be enough to run a lighting circuit.

It's not only about making sure you have enough available power on a new install, it's also about making sure an existing install can provide sufficient power for what you intend to use. suppose you have a company, and they are moving into another building, it's an existing building that was previously used as lets say a sewing factory, now sewing machines don't use much power, if the new company is an engineering firm using lots of electric welders, which do use a lot of power, then it would be pointless for them to move in, if although the building was big enough to house all their equipment, the supply wasn't big enough to run it all.

 

[SBS Dave]

Hi SUD,

A good way to solve your problem is to use the IET Estimation Method, using the formula   Pmax = gxP1, where Pmax  is the estimated maximum demand on an installation, P1 is the actual total installed load, usually on the basis of continuous duty and g is the diversity or de-rating factor applied to the particular type of installation.

For individual dwellings, the factor is 0.4, whereas in the Mechanical Engineering Industry, such as Metal Workers or Car Plants, the factor is 0.25. The Food Production Industry factor is about 0.8 and Public Buildings, including Shops, is about 0.7.

It is not a precise method, but it gives you guide as to what the overall load is likely to be.

SBS Dave

 

[SUD]

Thanks for your help. I would take the maximum rating for designing and here we assign 0.2 diversity factor for socket loads in industrial sector.

63Amps Socket ( P=63*440*1.732*.8 = 38KW * 0.2 = 7.6KW)

Here we are  going to install a socket box which comprises of a 63Amps and 32Amps socket. My question is what should be the breaker rating feeding this socket box?? I mean 63+32 = 95Amps or 100Amps MCCB or a 63Amps MCCB??

Thanks.

 

[Tony S]

Personally I would run two feeds, each with its own MCB.

Out of interest, what are these sockets feeding?
 

 

[SUD]

I have no idea about the future use of these sockets but i have to install Legrand Socket box which contains a 32Amps and 63Amps Industrial sockets.

Thanks.

 

[phil d]

As Tony has said, it really needs 2 feeds and 2 separate breakers, you cannot feed a 32 amp socket off a breaker any higher, it's maximum design current is 32amps and it should be protected by a device of the same rating, otherwise you could potentially end up with something very nasty happening.