UK Voltage Question

[Curly Gouger]

My plant has an inverter thats keeps tripping out
with an overvoltage error message.

I have taking readings from the meter in the main supply
panel with the following results.

ph1 - 435v
ph2 - 437v
ph2 - 433v

ph1-n - 249v
ph2-n - 253v
ph3-n - 249v

All phases were using around 500Amps at the
time, which is out average consumption.

So, my question is, are these voltages a bit high?
I was lead to believe that the UK voltage was now
around the 400/220 mark?

Thanks for any help.

Curly/

 

[cupra]

My plant has an inverter thats keeps tripping out
with an overvoltage error message.

I have taking readings from the meter in the main supply
panel with the following results.

ph1 - 435v
ph2 - 437v
ph2 - 433v

ph1-n - 249v
ph2-n - 253v
ph3-n - 249v

All phases were using around 500Amps at the
time, which is out average consumption.

So, my question is, are these voltages a bit high?
I was lead to believe that the UK voltage was now
around the 400/220 mark?

Thanks for any help.

Curly/

It does seem on the high side - but when is the inverter tripping? If it's tripping on decel, you may need a brake chopper and some braking resistors - or perhaps extending the decel ramp time will help. Also check the inverter setup - there may be a setting for supply voltage that will alter the OV trip level.

 

[Bill Lyons]

My plant has an inverter thats keeps tripping out
with an overvoltage error message.

I have taking readings from the meter in the main supply
panel with the following results.

ph1 - 435v
ph2 - 437v
ph2 - 433v

ph1-n - 249v
ph2-n - 253v
ph3-n - 249v

All phases were using around 500Amps at the
time, which is out average consumption.

So, my question is, are these voltages a bit high?
I was lead to believe that the UK voltage was now
around the 400/220 mark?

The UK "legal" voltage is now 230V -6% to +10%, i.e. a range of
216.2 to 253V.

This means that your voltages are on the borderline of being
too high, and if this is the on-load voltage at your equipment after
drops due to the impedance (resistance) of the supply, then the voltage
at the incoming terminals is probably a few percent higher, and
definitely a case for a complaint to your electricty supplier, who can
reduce the voltage by changing taps on the distribution transformer.

In talking to them you might find it helpful to have a look at
http://www.claudelyons.co.uk/energy_saving and particularly the section
"European Voltage Harmonisation" which will give you the correct
regulation (Statutory Instrument) to quote when they start arguing with
you.

The same technical note shows that a voltage reduction should be highly
beneficial and while people like us supply transformers and voltage
regulators, in this case it should be done by the electricity provider,
not at your expense.

 

[Curly Gouger]

The UK "legal" voltage is now 230V -6% to +10%, i.e. a range of
216.2 to 253V.

This means that your voltages are on the borderline of being
too high, and if this is the on-load voltage at your equipment after
drops due to the impedance (resistance) of the supply, then the voltage
at the incoming terminals is probably a few percent higher, and
definitely a case for a complaint to your electricty supplier, who can
reduce the voltage by changing taps on the distribution transformer.

In talking to them you might find it helpful to have a look at
http://www.claudelyons.co.uk/energy_saving and particularly the section
"European Voltage Harmonisation" which will give you the correct
regulation (Statutory Instrument) to quote when they start arguing with
you.

The same technical note shows that a voltage reduction should be highly
beneficial and while people like us supply transformers and voltage
regulators, in this case it should be done by the electricity provider,
not at your expense.

Thanks for the advice,

The voltages quoted were when running fully loaded.

They swing quite a lot higher than that off load
or at reduced load (have seen 265v ph-n)

We have our own HV transformer and we are on a
long rural HV line.

I will give the suppliers a call and see what that say....
..... last time I spoke to them I was told it was quite
normal to get high voltages off load.


regards, Curly/

 

[Bill Lyons]

On Friday, in article <[email protected]>

My plant has an inverter thats keeps tripping out
with an overvoltage error message.

I have taking readings from the meter in the main supply
panel with the following results.

ph1 - 435v
ph2 - 437v
ph2 - 433v

ph1-n - 249v
ph2-n - 253v
ph3-n - 249v

All phases were using around 500Amps at the
time, which is out average consumption.

So, my question is, are these voltages a bit high?
I was lead to believe that the UK voltage was now
around the 400/220 mark?

[previous response snipped]

Thanks for the advice,

The voltages quoted were when running fully loaded.

They swing quite a lot higher than that off load
or at reduced load (have seen 265v ph-n)

265 no load to 249 full load (the lowest you quoted) is a
variation of approx 6%, due to the "regulation" of your
transformer and cabling (and the incoming HV cable).

We have our own HV transformer and we are on a
long rural HV line.

That does make things a little different. The -6% +10% limits
apply if the electricity supply is at a nominal 230v.

For higher voltage supply to your own transformer, the supplier
is required to keep the voltage at the input of your transformer
within the limits of +/- 6% per paragraph 27(3)(c) of Statutory
Instrument 2002 No 2665 - The Electricity Safety, Quality and
Continuity Regulations, 2002.

[You can download your own copy at
http://www.legislation.hmso.gov.uk/si/si2002/20022665.htm ]

Does your transformer have taps - typically these might be
at +5% +2.5% 0 -2.5% -5% ?

Reducing the supply by 5% would bring your no load voltage
down to 252 and full load to approx 236 which would be much
better for the inverter - I presume it is labelled for nominal
415/240 or 400/230 supply?

I will give the suppliers a call and see what that say....
.... last time I spoke to them I was told it was quite
normal to get high voltages off load.

It is indeed normal to get high_er_ voltages off load.
The IEE's practice is to allow 4% for on-load drops within the
installation. Your 6% is a little high but not unusual.
(Essentially this is why the MV limits are +/-6% but the
LV limits are -6 +10%)

But the supplier has a statutory duty to declare the supply
voltage (to your transformer) and maintain it within the
regulations in the SI. Drops in the HV cable are part of
his responsibility.

As you have your own HV transformer, what happens after it is
up to you. If you can't drop the voltage by changing taps,
there are other solutions.

I realise this is a slightly different answer than before, but
things are different if the LV supply is from your own transformer.

Hope this helps but please feel free to contact directly by
email

 

[Nigel Turton]

is the load regenning back into the inverter? if so the DC link bus will
trip out on overvoltage, you could rectify this by fitting a resistor module
to the inverter or trying to up the overvoltage threshold on the unit above
150%