Document Number: 26018 For technical questions, contact: dc-film@vishay.com
www.vishay.com
Revision: 01-Jul-10 155
MKP 1840 M
AC and Pulse Metallized Polypropylene Film Capacitors
MKP Radial Potted Type
Vishay Roederstein
MEASURING THE COMPONENT TEMPERATURE
A thermocouple must be attached to the capacitor body as in:
The temperature is measured in unloaded (T
amb
) and maximum loaded condition (T
C
).
The temperature rise is given by T = T
c
- T
amb
.
To avoid radiation or convection, the capacitor should be tested in a wind-free box.
APPLICATION NOTE AND LIMITING CONDITIONS
These capacitors are not suitable for mains applications as across-the-line capacitors without additional protection, as described
hereunder. These mains applications are strictly regulated in safety standards and therefore electromagnetic interference
suppression capacitors conforming the standards must be used.
To select the capacitor for a certain application, the following conditions must be checked:
1. The peak voltage (U
P
) shall not be greater than the rated DC voltage (U
Rdc
)
2. The peak-to-peak voltage (U
P-P
) shall not be greater than the maximum (U
p-p
) to avoid the ionisation inception level
3. The voltage peak slope (dU/dt) shall not exceed the rated voltage pulse slope in an RC-circuit at rated voltage and without
ringing. If the pulse voltage is lower than the rated DC voltage, the rated voltage pulse slope may be multiplied by U
Rdc
and
divided by the applied voltage.
For all other pulses following equation must be fulfilled:
T is the pulse duration
4. The maximum component surface temperature rise must be lower than the limits (see graph max. allowed component
temperature rise).
5. Since in circuits used at voltages over 280 V peak-to-peak the risk for an intrinsically active flammability after a capacitor
breakdown (short circuit) increases, it is recommended that the power to the component is limited to 100 times the values
mentioned in the table: “Heat conductivity”
6. When using these capacitors as across-the-line capacitor in the input filter for mains applications or as series connected with
an impedance to the mains the applicant must guarantee that the following conditions are fulfilled in any case (spikes and
surge voltages from the mains included).
Voltage Conditions for 6 Above
ALLOWED VOLTAGES
T
amb
85 °C 85 °C < T
amb
100 °C
Maximum continuous RMS voltage U
Rac
U
Rac
Maximum temperature RMS-overvoltage (< 24 h) 1.25 x U
Rac
1.25 x U
Rac
Maximum peak voltage (V
O-P
) (< 2 s)
1.6 x U
Rdc
1.1 x U
Rdc
2
dU
dt
--------
2
0
T
dt U
Rdc
dU
dt
--------
rated
