MKP 385
Vishay BCcomponents
AC and Pulse Metallized Polypropylene Film Capacitors
MKP Radial Potted Type
www.vishay.com For technical questions, contact: dc-film@vishay.com
Document Number: 28152
168 Revision: 19-Mar-13
Not Recommended for New Design, Use New MKP385
This document is subject to change without notice.
THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
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/d
t
) 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 figure max allowed component temp 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
EXAMPLE
C = 4n7 1600 V used for the voltage signal shown in next figure.
U
p-p
= 1000 V; U
p
= 900 V; T
1
= 12 µs; T
2
= 64 µs; T
3
= 4 µs
The ambient temperature is 80 °C. In case of failure, the oscillation is blocked.
Checking the conditions:
1. The peak voltage U
p
= 900 V is lower than 1600 Vdc
2. The peak-to-peak voltage 1000 V is lower than 2 2 x 550 Vac = 1600 U
p-p
3.
The voltage pulse slope dU/dt = 1000 V/4 µs = 250 V/µs. This is lower than 4000 V/µs (see specific reference data for each version)
4. The dissipated power is 35 mW as calculated with Fourier terms and typical tgd.
The temperature rise for w
max.
= 6.0 and pitch = 10 mm will be 35 mW/9 mW/°C = 3.9 °C
This is lower than 10 °C temperature rise at 80 °C, acc. figure.
5. Oscillation is blocked
6. Not applicable
Voltage signal:
2 ×
⌠⎛dU⎞
2
⌡⎝ dt
⎠
× dt < U
Rdc
×
T
0
⎛dU⎞
⎝ dt
⎠
rated
ALLOWED VOLTAGES T
amb
85 °C 85 °C < T
amb
110 °C 110 °C < T
amb
125 °C
Maximum continuous RMS voltage U
Rac
0.7 x U
Rac
0.5 x U
Rac
Maximum temporary RMS-overvoltage (< 24 h) 1.25 x U
Rac
0.875 x U
Rac
0.625 x U
Rac
Maximum peak voltage (V
o-p
) (< 2 s) 1.6 x U
Rdc
1.1 x U
Rdc
0.8 x U
Rdc
Voltage
U
p
T
3
T
1
T
2
U
p-p
Time
