IG-287-EN version 03; 24/07/2020
24
Maintenance
General Instructions
transforma
.plur: Transformers with corrugated tank
and submerged in dielectric liquid from 3150 kVA
7.3. Regularity of maintenance
It is recommended to perform at least one annual inspection
of the following aspects:
1. Sealtight integrity
: check that the transformer does
not leak dielectric liquid.
2.
If the machine is fitted with oil level, internal pressure
and/or temperature indication instruments, check that
the levels or values measured are appropriate.
If there is a maximum temperature trailing needle,
it is very important to check that said maximum
temperature is within the transformer's normal
operating parameters.
3. Clean state
: check that the transformer is clean and
well conserved.
4. Noise
: check that the transformer does not produce
strange or untimely noises.
The requirements set out in the applicable legislation
on transformer stations and substations to protect
people and property which may be damaged by the
installations must also be met.
Operation
Elements to be
controlled
Regularity
Remarks
1
Thermometer
Once every 2 years
Check calibration, contacts and maximum
temperature value.
2
Terminal box
Once every 2 years
Check connections and clean any dirt.
3
Terminals
Once every 2 years
Check state and clean
4
Tap changer
Once a year
Move the tap changer through all positions.
5
Accessories with alarm and trip
contacts
Once every 2 years
Check the conditions of use, the contacts and
measure the electrical insulation of the circuit.
6
Fans (if fitted)
Once a year
In the event of an incident such as vibrations or
abnormal noises, or noticeable defects
7
Winding insulation level
Once every 6 years
If a change in results is detected after years of use of
the transformer or when comparing the previous test
data, carry out oil recirculation treatment without
applying a vacuum to the tank
8
Measurement of tan δ
Once every 6 years
In the case of inadequate values, carry out oil
recirculation treatment without applying a vacuum
to the tank.
9
Oil surface tension test
Once every 6 years
In the case of inadequate values, carry out oil
recirculation treatment without applying a vacuum
to the tank.
10
Oil acidity value
Once every 6 years
In the case of inadequate values, carry out oil
recirculation treatment without applying a vacuum
to the tank.
11
Oil general state test
Whenever any abnormal data is found in
operations 7 to 10
Take a sample of oil and carry out tests indicated in
Standard IEC 60422
12
Oil humidity content test
Whenever any abnormal data is found in
operations 7 to 10
Table 7.1.
Operations and maintenance frequency
