Transformer protection Pressure-Vacuum Gauge

[sparkview]

Hi all,

We are currently installing 4 new station transformer of 1600 kVA each as indicated on the nameplate below. As per the wiring diagram the transformer is provided with contacts for the following:
[ul]
[li]Thermometer (26Q)[/li]
[li]Liquid level (71)[/li]
[li]Pressure-Vacuum gauge (63V)[/li]
[/ul]

The Transformers are being protected by an ABB RET615 relay with included overcurrent and differential protection. The RET615 has spare input contacts that are directly connected to the tripping coil of the breaker. Would it be adequate to use the Pressure-vacuum gauge contacts as extra protection for the Transformer as well?

Your thought is highly appreciated.

Jairo

 

[stevenal]

Alarm, don't trip for low/high pressure. Note that the other devices provide tripping contacts.

 

[ScottyUK]

On the assumption that this transformer has a pressure relief device - a Qualitrol 208 or something similar - then I agree with stevenal. The PRD should directly trip the breaker.

 

[RRaghunath]

Is this transformer Nitrogen capped for oil preservation system!
Is the pressure-vacuum gauge to sense sudden build-up of pressure in the tank, suggesting internal fault similar to Buchholz relay in conservator transformers!
If true, the 63P contact (and not the 63V contact) to be wired for tripping the transformer.

Rompicherla Raghunath

 

[sparkview]

Hi all,

Thanks, for the prompt reply. The 1600 kVA Transformer has only a PRD without trip/alarm contacts as can be seen below. The alarm/ trip contacts are located on the Thermometer (26Q) and Liquid Level (71). In this case what should protect the transformer if internal faults should occur (e.g. internal short)?

Also, the powerplant decided not to include a differential protection functionality from the RET615, only the overcurrent protection.

 

[prc]

For an internal fault - if it is to ground, over current or differential relay plus PRD will protect. If it is a turn to turn fault, Buchholz will take care. Please recheck, normally PRDs are always provided with alarm/trip contacts.