Transformer bonding

[Mike_RPI50]

Could someone confirm this please.

If I need to use a 600 to 240 step down transformer i need to bond leg 2 and leg 3 to ground correct?

See attached picture.

thanks

 

[keithkyll]

Yes, for US style power. 120V on each leg. Fuse 1 and 4.
For European, ground leg 4 only. Fuse on leg 1.

 

[Mike_RPI50]

This system will be going to Europe. If I am getting correctly our saying in European standards L1 of the 240 should be fused and L2 should be bonded to ground.

That seems very odd.

cheers

 

[BryanG]

If you link and ground 2&3 that would be a centre grounded transformer, which in itself is not a problem, but all your control would need to switch on both sides of the circuit. The standard voltage Phase to Neutral in Europe is 230V a.c. so I would expect you to wire it for 240V output and then ground one output leg, the overcurrent protection should then obviously be in the ungrounded leg. Looking at the transformer terminals I would expect to ground at terminal 4. If there is any chance of a person coming in to contact with the voltage then personally I always add what in Europe is called an RCD (Residual Current Devices) or ELCB (Earth Leakage Circuit Breaker)

 

[Mike_RPI50]

Thank you very much that answered my question.

Has for the ELCB they are asking for a earth leakage relay it's basically a ct that goes around the 3 phase 440. It has built in dry contacts and a analog output. But it is not very clear how they what it to be implemented with the controls it 30ma not personal protection 5ma rated.

Anyone has experience with these?

 

[shooter]

on 600 volts there is no RCD needed or used.
however after every transformer you will need a RCD (or more) as the transformer is isolating circuits from the net.
ground one leg
have them in every outgoing circuit of 30 mA
You must use dtdp for the OCR.
there are combinations available for inside houses etc.

 

[iant]

the Dot is the clue to your connection.
Note
The 120V output has the two secondary coils in Parallel.
The 240V output has them in series so any grounded connection to terminals 2~3 would tie the voltage down to 120 V
If you require to ground the secondary than whichever terminal, 1 or 4, you choose will become the Neutral point.
An RCD is only usable then as there will be the posibility of detecting a leakage to ground.

 

[iant]

Thank you very much that answered my question.

Has for the ELCB they are asking for a earth leakage relay it's basically a ct that goes around the 3 phase 440. It has built in dry contacts and a analog output. But it is not very clear how they what it to be implemented with the controls it 30ma not personal protection 5ma rated.

Anyone has experience with these?

a three phase ELCB uses the total difference of currents between each of the three phases. the mathmatical value is zero.

this is normally tied in with a trip coil to a 4 pole 3 phase CB.

 

[James Mcquade]

Mike,

Not to rain on your parade, but you are forgetting one major component, European standards.

not everyone is 60 hz, 440 volts!
you need to consult with your end user to see what their power specifications and needs are.

for example, in England, there is no 120 volts, its 220 volts.
3 phase power is 380 volts, not 240, 480.

there are also electrical requirements that must be met that are not required in the US.

regards,
james

 

[TurpoUrpo]

Its not really that hard to use google.

http://en.wikipedia.org/wiki/Mains_electricity_by_country

Most of eu is 230V, that is 400V between phases. 50Hz.

 

[iant]

James You are correct for Phase to Phase and Phase to Neutral/Ground voltages.
However transformer output voltages are not frequency dependant
it is the turns ratio
so 600 to 240 is posible - 1 : 2.5 ratio
the Frequency will follow the supply frequency.
And
a 240 V 50hz Machine will not like 240 V 60 Hz for long

 

[Mike_RPI50]

breaker

a three phase ELCB uses the total difference of currents between each of the three phases. the mathmatical value is zero.

this is normally tied in with a trip coil to a 4 pole 3 phase CB.

I had a feeling that's how it needed to be implemented my boss said not to worry about it. Why a 4 pole breaker 440 3 phase has no neutral.

 

[seppoalanen]

I don't know witch is destination country in Europe, but here comes some example drawing for you. Never needed 4-pole CB for 3-phase system here if there are not 3-phase socket outlets e.g. for welding or other tools.

 

[iant]

I had a feeling that's how it needed to be implemented my boss said not to worry about it. Why a 4 pole breaker 440 3 phase has no neutral.

A start point transformer has a neutral
440V Phase to Phase
240V Phase to Neutral

 

[Oceansoul]

Mike,

Not to rain on your parade, but you are forgetting one major component, European standards.

not everyone is 60 hz, 440 volts!
you need to consult with your end user to see what their power specifications and needs are.

for example, in England, there is no 120 volts, its 220 volts.
3 phase power is 380 volts, not 240, 480.

there are also electrical requirements that must be met that are not required in the US.

regards,
james

Thats not entirley correct.
Here, Single phase is 230V (240V). Three phase is 400V (415V). The numbers in brackets are the old UK standard prior to harmonisation with Europe.