IG-287-EN version 03; 24/07/2020
19
General Instructions
transforma
.plur: Transformers with corrugated tank
and submerged in dielectric liquid from 3150 kVA
Start up
6. Start up
6.1. Transformer check before commissioning
Once the transformer is connected to the power networks,
and before connecting the electrical power source, the
following checks should be performed:
1.
Check that the network values and the transformer
rated voltage match.
Natural esters have higher freezing points than those
of mineral oil. Therefore, the liquid could freeze during
prolonged exposure to temperatures below 0 °C. The
transformer can be powered in these cases, although
these situations should be avoided wherever possible.
2.
If the machine has these instruments, check the correct
oil level on the oil level indicator or Buchholz relay.
3.
Feed the no-load transformer and check its correct
connection and regulation by measuring the values
in the secondary. Where the transformer has natural
ester-type dielectric liquid and is powered after a
prolonged period of exposure to temperatures below
0 °C, the dielectric fluid might be solid. Once the load
transformer has been powered, it will recover its usual
liquid stage.
4.
Regulate the transformer's voltage using the
corresponding tap changer, taking into account the
following safety precautions:
Failure to follow these safety precautions may result in
death by electric shock or irreversible damage to the
transformer or to the electrical installation.
If the transformer has a natural ester as dielectric
liquid and has been exposed for a prolonged period
to ambient temperatures below 0 °C before being
powered, the fluid might be solid. The tap changer
control CANNOT be used under these circumstances.
The transformer must be warmed up until the fluid
is liquid enough for the tap change control to be
handled.
a.
If the transformer has a no-load tap changer:
i.
The no-load voltage tap changers must always
be operated without electrical power, ensuring
the handle is well locked and in its working
position.
ii.
Check that the electrical voltage applied
matches the transformer's rated voltage. In the
case of anomaly, contact the
Ormazabal
.
iii.
If, after commissioning the transformer, it is
necessary to perform an adjustment, follow the
safety instructions specified in section 6.1 of this
general instructions manual.
d.
If the transformer has an on-load tap changer (OLTC),
follow the specific instructions for this changer as
supplied with the transformer.