Which Connector is Live in Transformer ?

[Furkin]

I have some Chinese lighting transformers by Sunnycai.
Unfortunately they don't say which terminal is for the live (230v) feed.

There are the two usual primary connectors. The left one goes to a Capacitor (yellow box type) first, and the right one goes to a Resistor first.

Can anyone tell from this which is the live connector please ?

I could - if I have to - upload a picture to help you to help me.

I have e-mailed Sunnycai but don't know if they will reply.

Thanks folks

 

[ban-all-sheds]

Why should it matter?

The voltage on the live with respect to neutral varies from +325V to -325V 50 times a second...

 

[Furkin]

Left terminal goes to the yellow Capacitor.
Right terminal goes to 'blue' Resistor.


View media item 19933

 

[TicklyT]

As BAS said, you have an alternating current supply, and no earth connection to reference for 0 Volts, so it doesn't matter which way round live and neutral are connected.

Incidentally, that's an SMPS, not a transformer. It fulfils a similar function to a transformer, but by different methods.

 

[Furkin]

Thanks guys,

I thought that the a/c current needed to go a certain way through the system/components so that each component in turn can do its job.

I had no idea it was interchangeable.

Sorry if my calling it a transformer (as opposed to SMPS) confused anyone,,,, it's just that it states that on the box.

Whats the difference between the two, and which is best ? When we buy 'transformers' how do we know which we are getting ?

In the mean time, my immediate concern is answered - thanks again.

 

[ban-all-sheds]

I thought that the a/c current needed to go a certain way through the system/components so that each component in turn can do its job.

I had no idea it was interchangeable.

Because it's AC it changes direction 50 times a second.

Whats the difference between the two, and which is best ?

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

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

Transformers are simple, and don't mind being dimmed (although many dimmer switches don't like the inductive load that they present), and are heavier, bulkier and more expensive. On their own they provide no voltage regulation.

SMPSUs are smaller and lighter, don't always like being dimmed (although these days most are OK). They can be designed to provide good regulation (e.g. the ones in computers), but ELV lighting ones are usually pretty basic.

When we buy 'transformers' how do we know which we are getting ?

If it's small and not very heavy it's a SMPSU.

 

[Stoday]

Because it's AC it changes direction 50 times a second.

If that were the case, he'd have a 25 Hz supply.

Last 25 Hz public supply was at Stavely, Derbys, discontinued in 1965. Keep up to date, BAS.

 

[Taylortwocities]

Alas, poor Stoday, I knew him well.....

I just love it when someone puts their head above the parapet.
BAS was off last week and his batteries have been recharged!

 

[RF Lighting]

1965

Ahh 1965. I remember it well.

The same year that "protective multiple earthing" - any multiple earthing other than that permitted by Regulations 4 and 8 of the "Electricity Supply Regulations, 1937" had to be approved by the Minister of Power with the concurrence of the Postmaster General. Consents were given to six Area Boards to use p.m.e. in any part of their area of supply and it began to be introduced on a significant scale in medium-voltage distribution systems, leading to the development of c.n.e cables if I'm not mistaken.

 

[ban-all-sheds]

Oh poo.

 

[Paul_C]

I believe there are still a few industrial customers supplied at 25Hz in western New York state, fed from the old Niagara Falls generating plant.

 

[Stoday]

Regulations 4 and 8 of the "Electricity Supply Regulations, 1937" had to be approved by the Minister of Power with the concurrence of the Postmaster General.

I know you are trying to help BAS by referring to recent regulations but you are assuming that he is familiar with the Act that it supplemented. I am referring, of course, to the Electric Lighting (Clauses) Act 1899, which was not repealed until 1989.