ION9000 MV wiring

[Szymon_Hochół]

Hello Experts,

I am looking for some guidance in wiring and configuring ION9000 in MV network.

The system is 6kV DELTA, and the switchboard has 3 voltage transformers. They are connected like this:

However, for a DELTA system, ION9000 installation manual does not include such setup. It presents direct connection or using two VTs:

How would you wire and configure (volts mode, nominal voltage etc.) the meter in such case? 

Thank you in advance.

[Charles_Murison]

Hello @Szymon_Hochół ,

I will want to confirm with an engineer, will let you know.

Regards,

Charles

[DanL]

The secondary of the 3PTs are connected together and form a COMMON potential and a 4th wire for voltage.

The PT SECONDARY wiring always determines the volts mode used with ION meters.

There are two good options:

Use 4W-WYE volts mode and connect meter's VN measurement terminal to ground (the PT common). The meter's line-to-neutral registers will report the system line-to-ground voltage. Line-to-line voltages will reflect system line-to-line voltages (of course)

OR

Use DELTA volts mode and connect only V1, V2 and V3 measurement terminals (just like a "3 wire direct delta connection" to the PT secondary). Now the meter will only report line-to-line system voltages.

[Szymon_Hochół]

Thank you @DanL.

There is another thing that's not clear for me: choosing volts mode affects the nominal voltage that I should configure. With 4W-WYE, I should use L-N voltage as nominal (which is not there, because there is no N), with 3W-DELTA I should use L-L voltage. This parameter will affect sag/swell detection and harmonics calculations, according to meter's user manual. So woudn't the use of 4W-WYE result in some wrong calculations?

And one last thing, If I use the DELTA mode, and connection that you described - can we leave VN, VE, V4 be not wired at all?  Or should we ground it as indicated on the drawing? If these need to be grounded, why not use the fourth wire from PTs (which is ground)? But that makes the wiring the same as for 4W-WYE. Or am I wrong?

Thanks

[Charles_Murison]

Hello @Szymon_Hochół,

It is possible to configure the meter to use VLL information only. Some of the changes are just a setup register (like with sag/swell module) other changes may be linking the LL input rather than LN. If you want to explorer this more I would recommend contacting technical support.

Regarding the wiring I would have to defer to Dan.

Regards,

Charles

[DanL · Accepted solution]

nominal voltage that should be configured:
4W-WYE use L-N rms Primary voltage as nominal (which in your case is line-to-earth because that is how the PT primaries are wired)
DELTA use L-L rms Primary voltage

The "Vnominal" setup register in the Factory module in ION9000 default template/framework is linked to the input of many other modules. Right+click on the register and select "Show Connections"

If you use the DELTA volts mode, and the connection that you described, you could leave VN, VE, V4 not wired at all, but we recommend connecting those terminals as indicated on the drawing. If possible, you should use the fourth wire from PTs (which is ground). That makes the wiring the same as for 4W-WYE, and you can switch over at a later point if you wish to measure line-to-earth voltages (using the meter's VLN output registers in 4WYE mode).

[Szymon_Hochół]

Thank you for your support @DanL , @Charles_Murison .

I'll let you know how it works once we get to install the meter.

Have a good day!

[conradvr_hexeis]

Hi @DanL,

This is similar to an issue Hexeis have a few years ago with the ION7650 used on 3W Delta Networks with Star-Star PT installations.  Over the last 10 years Hexeis has never had an ION installation in Australia that uses the PT arrangement as shown in the installation sheet.  Most of the PT installations are used for Protection relays hence the Star-Star design.

Hexeis consulted with Schneider technical support at the time and the information received noted (original case number 1381097).

The feedback received at the time was using Delta mode results in measuring voltages across 2 PT windings instead of 1 so this impacts accuracy.  I also recall some chat about the effect of the phase shift caused by the PTs.

Since then Hexeis has always used the Volts Mode 4W-WYE and adjusted the Nominal Voltages etc to suit.

It would be very useful to have a factory document that displayed the alternative wiring diagrams, provided recommended configurations and noted the impact on accuracy and other metering performance.  Can this please be provided?

Regards,

Conrad

[conradvr_hexeis]

Hi @Szymon_Hochół 

With the Sag/Swell module you can also use the Setup Register "Use Vll Always" to use V line to line voltages even when their are line to neutral (earth) voltages available i.e. when using 4W-WYE.

Regards,

Conrad

Hexeis