BUSHING METAL PART MELTING

Objective: Electrical Connections are very important if they improper it may cost the following effects on man and materials, and ready to destroy the whole system also, The poor connection in Bushing metal part causes the following,

1. Melting in any side of connections, usually low melting point material side.
2. Over heating in contact places
3. Over heating increases chances of early oil leak in bushings
4. Servicing difficult once the part melted/ burred
5. The over heating will affect the next weakest point which is near.

Once it start melt it is unable to replace it may possible to cut and remove the entire metal part then only it possible to change

Further detailed photos you may visit www.sagar33@vox.com

TRANSFORMER TESTING AT SITE

Everyone knows before commissioning or charging any equipment it must be need to test before putin to service, like that the new transformer is also need to ensure everything is fine. So, some tests are required to confirm. those are all called Pre-commissioning tests.some important tests are mentioned here for easy ref,

i) Insulation Resistance or Meggar Value with PI (Polarization Index)
ii) Turns / voltage Ratio
iii) Magnetic Balance
iv) Magnetizing current
v) Oil tests (BDV, PPM and DGA (for future ref))
vi) Protections (Differential, IDMT, Bucholz Relay,OTI, WTI, PRV, OSR, MOG, Fans and pumps)
vii) Operation of OLTC or OCTC/OCKT
viii) Vector Group Test

Testing methods will be described in next post.

TRANSFORMER TESTING

As per IS 2026 the following Routine tests are carrying out in transformers at testing stage.
1. Measurement of Winding resistance
2. Voltage Ratio/ Ratio Test
3. Measurement of Impedance voltage/ Short Circuit impedance
4. Measurement of NO-Load loss and current
5. Dielectric tests (Induced Over Voltage and Separate Source Voltage)
6. Magnetic Balance and Current
7. Load Loss
8. Insulation Resistance
9. Vector Group
10. Oil BDV
11. Capacitance and Tan delta

Tests at site will be discussed in next post.