Characteristics of "all-film" medium voltage capacitors

 

 
  • Variation of W/kvar losses as a function of temperature

In relation to the former generation of "mixed" type (paper + film) dielectric capacitors, synthetic "All-film" type dielectric capacitors have a much longer service life, due to their very high thermal stability related to very low power losses due to the removal of the paper and the remarkable chemical stability of the liquid dielectric enabling:

- A high partial discharge absorption capacity
- A high dielectric resistance to transient excess currents and excess voltages
- A very low variation of capacitance as a function of temperature


  • Variation of capacitance C (µF) as a function of temperature

Average loss factor:
- 0.15 W/kvar at power-up
- 0.1 W/kvar after 500 hours of operation

Variation of capacitance as a function of temperature:
- Mean: 2 x 10-4/°C

Internal discharge device:
- Internal discharge resistors reducing the residual voltage to 75 V in 10 minutes after disconnection of the supply

Frequency:
- Standard: 50 Hz (60 Hz on request)

Reference standards:
- French: C 54 102
- International:
IEC 871.1 and 2 (supply capacitors)
IEC 110 (air or water-cooled capacitors for induction furnaces)
- German:
VDE 0560/4
VDE 0560/9
- British : BS 1650
- Other standards on request


  • Variation of W/kvar losses as a function of operating time
    Losses = F (oper. time)

Admissible overloads
- Current : 1.3 I nominal continuously
- Voltage (between terminals) :
1.1 U nominal 12 h/24 hours
1.15 U nominal 30 minutes/24 hours
1.2 U nominal 5 minutes/24 hours
1.3 U nominal 1 minute/24 hours

Standard insulation levels (phases/ground) for unit capacitors
- Highest voltage for equipment Um (RMS)

2.4

3.6

7.2 12 17.5 24

- Test voltage at industrial frequency (duration: 10 sec) (kV)

8

10

20 28 38 50

- Lightning shock resistance voltage (peak value)

35

40

60 75 95 125

Individual tests
- Measurement of capacitance and losses
- Voltage test between terminals, i.e.:
- 2.15 U nominal 10 sec AC voltage
- 4.3 U nominal 10 sec DC voltage
- Voltage test between joined terminals and ground at industrial frequency
- Discharge device and cell integrity check