B32671L EPCOS [EPCOS], B32671L Datasheet - Page 18

• Manufacturer Part Number: B32671L
• Description: Film Capacitors Metallized Polyester Film Capacitors (MKT)
• Manufacturer: EPCOS [EPCOS]

Operation at overvoltages during heating and ignition of lamps (T
In lighting applications, the capacitors can be subjected to overvoltages during the heating and ig-
nition periods. An overvoltage occurs when the operation voltage exceeds the permissible
AC voltage at the resonant frequency f
For a repetitive application of on/off switching pulses (as for example in the life tests applied by
electronic ballast manufacturers), limits have to be imposed on the time periods under overvolt-
age and on the duty cycle, in order to keep the capacitance value within the required margins:
The maximum drift of capacitance as a function of both parameters is provided graphically in the
following pages.
Please read Cautions and warnings and
Important notes at the end of this document.
The overvoltage time t
The maximum duty cycle of the overvoltage is given by
where V
and V
(given by the “permissible AC voltage versus frequency f” graphics in theprevious pages).
The drift of capacitance depends on the V
which is calculated in hours as follows:
(N
where N
i
t
OV
RMS
) / 3600
RMS,ov
i
is the number of overvoltage impulses and t
is the permissible AC voltage for continuous operation at the resonant frequency f
B32671L ... B32672L
High V AC, high temperature (wound)
is the RMS voltage during period t
OV
should be less than 1 sec.
r
.
Page 18 of 31
pp
attained, and the total time under overvoltage,
OV
OV
is expressed in seconds.
A
40 C)
r