Kva to Mw
- Thread starter Dan1983
- Start date
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How did you come by that answer. Did you incorporate power factor in your calcs ?
In a fashion yes, but not sure that I calculated this right. Its seems low to me.
If I have under calculated that would be great as i need as much available watts/amps I can get.
From a calculation I did I get that
5000Kva over 3 phases would give around 12,500amps
Its doesn't have to be 100% accurate I just need an idea of what a 5000Kva supply from the electricity board would give you in usable watt/amps.
If I have under calculated that would be great as i need as much available watts/amps I can get.
From a calculation I did I get that
5000Kva over 3 phases would give around 12,500amps
Its doesn't have to be 100% accurate I just need an idea of what a 5000Kva supply from the electricity board would give you in usable watt/amps.
Switchgear would not affect the available supply if suitably rated.
5000kVA@400V = 5000000/(1.73x400)
= 7225 A per phase (approx)
That is the maximum current per phase that the Tx can deliver (if continously rated)
However depending on the nature of your load there may be power factor to consider (if there are a lot of inductive loads) which means not all of this current will be able to contribute to the real power (Kw)
Kw = Kva x PF
5000kVA@400V = 5000000/(1.73x400)
= 7225 A per phase (approx)
That is the maximum current per phase that the Tx can deliver (if continously rated)
However depending on the nature of your load there may be power factor to consider (if there are a lot of inductive loads) which means not all of this current will be able to contribute to the real power (Kw)
Kw = Kva x PF
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Surely this is being over complicated
5000KVa = Maximum power of 5000 kW or 5MW in ideal circumstances (Zero phase lag)
Power factor will reduce that figure
5000KVa = Maximum power of 5000 kW or 5MW in ideal circumstances (Zero phase lag)
Power factor will reduce that figure
Not sure what scenario you have but, Primary DNO 33kv/11kv substations only have a 10MVA transformer installed. so if your looking for a 5MVA supply youll be looking at an 11kv dual feeder HV supply and may even need a new primary DNO substation to support your loading, Not many networks have 5MVA to spare. I know Scot Power will only supply upto to a MAX of 1MVA of load at LV, and thats including a dedicated double secondary substation. So like spark123 says, its time to call in the consultant and electrical engineer. and knowing how much these types of supply cost, get ready to see your bank balance nosedive!!!!!
You will not get a supply of 5MVA at low voltage. You'll only get a connection at high voltage, almost certainly 11kV. For that size, you would normally have a secure supply, which means two feeders from the primary substation (132kV or 33kV to 11kV) or a loop from the HV ring main.
You will have to supply a HV panel with two incoming 11kV isolators and a bus section metering circuit breaker. Also 11kV breakers for each of your 11kV to LV transformers, plus the transformers themselves.
The DNO will charge you the full cost of the work on their network, probably the two feeders from the primary and the circuit breakers controlling them. Also you'll have to pay for any reinforcement of the 33kV network if there is not enough spare capacity at the primary.
That's going to cost a lot. If you ask for more power than you need, you'll not only pay for the extra unnecessary capacity, but you'll also be stuck with Availability charges for the extra for five years.
Most organisations wanting that size of supply would employ a utility consultant to ensure they ask for no more capacity than necessary.
You will have to supply a HV panel with two incoming 11kV isolators and a bus section metering circuit breaker. Also 11kV breakers for each of your 11kV to LV transformers, plus the transformers themselves.
The DNO will charge you the full cost of the work on their network, probably the two feeders from the primary and the circuit breakers controlling them. Also you'll have to pay for any reinforcement of the 33kV network if there is not enough spare capacity at the primary.
That's going to cost a lot. If you ask for more power than you need, you'll not only pay for the extra unnecessary capacity, but you'll also be stuck with Availability charges for the extra for five years.
Most organisations wanting that size of supply would employ a utility consultant to ensure they ask for no more capacity than necessary.
Could not have put it any planer or simpler!
Most will use a utility contractor, with the majority using their local DNO......
It is just far easier.
It is just far easier.
You would be tackling this at the wrong end. The requirements for the installation would depend on the number of loads connected, mix of inductive/resistive loads, which loads have high starting currents, voltage drop limitations, allowance for spare future capacity and the kVAr of Power Factor Correction for an economic return. Having analysed all these factors, the decision is required on how much redundancy you want on the incoming supplies i.e. whether 2, 3 or 4 transformers.
Transformers will operate for a short period on an overload situation; but this should be avoided as it will cause voltage drop problems. Your 5MVA equates to 5MW in theory; but most large installations have a PF of around 0.85 unless there is PFC plant installed; Your 5MVA is equivalent to 5 times 0.85 = 4.25 MW but there is the transformer efficiencies that have to be considered, this will depend on how many and what % loadings. Software programs are used by project houses for these complex calculations; and relying on input from experience.
It's straightforward for those who are accustomed to this work, certainly not DIY and not for those with basic knowledge of electrics.
Regards
Depending on the size of the site you would likely be utilising several trannies distributed accordingly.
Maybe Dan1983 is looking for plenty of spare capacity rather than just enough to satisfy his current forecasts.
In this case he should look at the spare capacity that's available at various levels in the local network. If he asks for more than the spare capacity that's available, costs jump up because 1) connection may be made further up the network, and/or 2) the network may need to be reinforced.
Network loading information is available in the form of the "Long Term Development Statement". All DNOs have them; EDF charge £50 for each of its three areas.
A good utility consultant will use these to estimate the capacity for which cost jumps will occur so that you can ask for the most cost effective capacity.
What you should never do it to ask the DNO for this assessment: they have a conflict of interest. If a consumer pays for a reinforcement that's greater than what he needs, the DNO can use the excess capacity for free.
In this case he should look at the spare capacity that's available at various levels in the local network. If he asks for more than the spare capacity that's available, costs jump up because 1) connection may be made further up the network, and/or 2) the network may need to be reinforced.
Network loading information is available in the form of the "Long Term Development Statement". All DNOs have them; EDF charge £50 for each of its three areas.
A good utility consultant will use these to estimate the capacity for which cost jumps will occur so that you can ask for the most cost effective capacity.
What you should never do it to ask the DNO for this assessment: they have a conflict of interest. If a consumer pays for a reinforcement that's greater than what he needs, the DNO can use the excess capacity for free.
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