Procedure to get BM working after bushings change

Created by Patrícia Siqueira, Modified on Wed, 4 Oct, 2023 at 3:39 PM by Patrícia Siqueira

This procedure's principal goal is to present recommended actions in the bushing monitoring after changing the bushing or the asset itself in one or more phases of a three-phase bushing set.

Needed information

To proceed with the steps of this document, you will need the pieces of information below:

New bushings nameplate;
Last bushings test data, if it is possible.

Steps to get BM working again

Reprogram alarms and initial values parameters

1. Following the step below, go to the device's initial values configuration screen.

2. Configure the tangent delta and capacitance initial values as the information provided by the most recent test. If the bushing test does not exist, consider the bushing nameplate values.

3. Navigate to the alarm configuration screen.

4. Configure the tangent delta and capacitance alarms in automatic or manual mode. The standard adjustment values provided by the norm are listed below.

	Manual mode	Automatic mode
High capacitance	1,03 * nameplate value	3 %
Very high capacitance	1,05 * nameplate value	5 %
High tangent delta	2 * the nameplate value or 0,7 (the higher value)	100 %
Very high tangent delta	3 * the nameplate value or 1,05 (the higher value)	200 %

Recalculate the reference values

⚠ Ideally, the reference values recalculation procedure should be done after energizing the transformer and confirming the leakage current consistency read by BM.

Then, you can avoid inconsistency and spurious points in the references bank. That could harm BM calculus in the future.

1. Following the navigation below, described step by step, recalculate the values reference from the set which had its bushing changed.

2. Press the P key until comeback showing the default screen. At this BM measurement screen, navigate to the number of samples screen. The screen displayed should be like the image below

3. If the transformer is powered, wait a few seconds and verify if the number of samples increases. The total increasing time is around 4 minutes.

4. After approval, the BM will initiate the learning. After the banks changed the mode to Calculus, it is possible to download the BM data as the BM download log guide and send it to our SAC team by e-mail at [email protected]. So the bank can be verified by Treetech specialists. And if needed, they will suggest an intervention.

If you have any problems or difficulties with the procedure, please do not hesitate to contact us!

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