# Thread: ALC of a transformer with two different sources on different busbars

1. Bronze Partner
Join Date
01.03.2018
Posts
6

## ALC of a transformer with two different sources on different busbars

Hi,

I have two busbars with two different sources (source Voltage2 at busbar I and Voltage3 at busbar II). A bay is connected to these bus bars with two disconnectors (Q1 and Q2). Furthermore the bay is connected to a transformer (respectively the transformer is a part of the bay). Between the switches and the transformer there is a circuit breaker (Q0) and another disconnector (Q9).
For the transformer I used a combi-element with ALC function type Transformer. For the Source (Quelle) I choosed the Voltage2 [11] and for the Recovery source (Quelle für Rückspeisung) UNDEFINED [0].
If the bay is connected to busbar I, the transformer takes over the colour of source Voltage2. But if the bay is connected to busbar II, the transformer doesn’t take over the colour of source Voltage3, because it’s defined that the source is Voltage2.
I would like to know if it’s possible to change the colour of the transformer without the knowledge of the source. Is it possible to pass the colour/ALC to the other side of the transformer?

Thank you

## Re: ALC of a transformer with two different sources on different busbars

Hi ansiem,

if you want to forward  the color from primary side to secondary side (and not transform it to another source) you could just use a switch.

Regards,
Felix

3. ## Re: ALC of a transformer with two different sources on different busbars

Hi ansiem and welcome to the forum!

I'm quite curious about the use-case behind this question as redundant busbars usually have the same voltage level; so in your case either Voltage2 or Voltage3, not both.
For transformers it's the same - you always transform the voltage from one primary side to 1-2 secondary sides (depending on the transformer type) e.g. 30kV=>13.8kV.
You can't tell such a transformer to now have 110kV at the primary or secondary side - and this is what you would do in fact.

Best regards,

KlemensN

4. Bronze Partner
Join Date
01.03.2018
Posts
6

## Re: ALC of a transformer with two different sources on different busbars

The voltage level of both busbars is the same, but I have the case that these busbars are provided by different electrical sources (two different generators). I would like to see which generator feeds the transformer. Of course if the busbars are connected there should be a synchronization. My idea was to create two different ALC sources, which have different colours, but same voltage level.

## Re: ALC of a transformer with two different sources on different busbars

Hi ansiem,

if you want to forward  the color from primary side to secondary side (and not transform it to another source) you could just use a switch.

Regards,
Felix

6. ## Re: ALC of a transformer with two different sources on different busbars

Hi ansiem!

- If feed-forward then it is the ALC source (or the ALC-sources if multiple supply) which colours the line straight before the transformer (Nr. 1 in the figure attached if feed-forward)
- In reverse feed it is the same but with other direction

The output side of the transformer (Nr. 2 in the figure attached if feed-forward) however does not care about what source currently feeds the transformer, it always supplies connected ALC-lines with the source defined within the ALC-configuration of the transformer depending of feeding-direction, e.g.:

- Transformer A is fed in forwards direction by Voltage2 and transforms to Voltage3 => input: Voltage2, output: Voltage3
- Transformer A is reverse-fed by Voltage3 and transforms to Voltage2 => input: Voltage3, output: Voltage2

You do not use transformers for passing-through ALC-sources without transforming to different voltage levels; so I can only promote Felix' answer to use a switch instead of a transformer.

Best regards,
KlemensN