TOPlist

Target values of insulating oils from transformers according to the Czech power transmission system requirements.


Measured
value
[units]
Before
filling
the machine
Before
putting in
operation2)
In 5 years
guarantee
period
operation4)
Periodical measuring3)
Normal
Deteriorated
Breakdown voltage [kV/2.5mm]
 >70
 >70
>70
 <60
Neutralization value [mgKOH/g]

<=0.04
 <0.08
 >0.1
Water content
[g/t]
 <=10
 <=10
<20
 >25
Interfacial tension [mN/m]

>=355)
 >45
 <40
Dissipation factor at 90oC [.10-2]
 <0.1
 <0.2
 <=0.6
 <1.5
 >6
Inhibitor content [%]
 >=0.30
 >=0.30
>0.20
 <0.15
PCB content
[ppm]
 <1



Sediments
<
 No

Total gas volume [%]
<0.5
 <1
 <2
 >3
H2

<60 ppm
 <100 ppm
 >150 ppm
CH4+C2H4+C2H6

<200 ppm
 <400 ppm
 >800 ppm
C2H2

<10 ppm
 <10 ppm
 <10 ppm
CO

<400 ppm


Notes:
  1. At periodical measuring, the 30% value deterioration must be consulted with Czech power transmission system.
  2. Measured after assembling before putting in operation.
  3. Values outside the set limits may indicate possible defects. Measurements carried out by other laboratory or methods are necessary. The measuring intervals are halved.
  4. Applies to the oil filled in a new machine.
  5. Measured according to ISO 6295 (tensiometric measuring)

According to Preventive maintenance guidelines of Czech power transmission system 3/1998



(c) 1999 - 2011 ELDIAG Ltd.