Datasheet

8© KEMET Electronics Corporation • KEMET Tower • One East Broward Boulevard F3116_C4AF • 7/29/2020
Fort Lauderdale, FL 33301 USA • 954-766-2800 • www.kemet.com
Power and AC Film Capacitors – Printed Circuit Board Mount Power Film Capacitors
C4AF, Radial, 2 or 4 Leads, 250 - 500 VAC, for Harsh Environment AC Filtering (Automotive Grade)
Power Losses & Hot Spot Temperature Calculation cont.
Limits for the formulas
The limits listed below should not be exceeded:
T
HS
= T
a
+ ∆T
HS
≤ (T
HS
)
MAX
MAX
i
i
VACfV ≤
∑
2
)(
1.
RMS
MAX
i
i
IfI ≤
∑
2
)(
2.
T
HS
= T
a
+ ∆T
HS
≤ (T
HS
)
MAX
MAX
i
i
VACfV ≤
∑
2
)(
1.
RMS
MAX
i
i
IfI ≤
∑
2
)(
2.
T
HS
= T
a
+ ∆T
HS
≤ (T
HS
)
MAX
MAX
i
i
VACfV ≤
∑
2
)(
1.
RMS
MAX
i
i
IfI ≤
∑
2
)(
2.
where Ta is the ambient temperature (steady state temperature of the cooling air owing around the capacitor, measured at
100 mm of distance from the capacitor and at a height of 2/3 height of the capacitor).
Example of calculation
P/N: C4AF9BW5100T3JK P
D
(50) = 2 * π * 50 * 10 * 10
−6
* 310
2
* 7 * 10
−4
=0.211 [W]
Rated V
RMS
= 310 [V
RMS
] P
D
(15,000) = [7.9
2
/(2 * π * 15,000 * 10 * 10
−6
)] * 7 * 10
−4
=0.0463 [W]
Rated I
RMS MAX
= 16.6 [A] P
J
(50) = 4.2 * 10
−3
* [(2 *π * 50 * 10 * 10
−6
* 310)
2
] = 0.00398 [W]
R
s
= 4.2[mΩ] P
J
(15000) = 4.2 * 10
−3
* 7.9
2
= 0.262 [W]
R
th
= 18 [°C/W] P
T
= 0.211+0.0463+0.00398+0.262 = 0.523 [W]
Fundamental Frequency F
1
= 50 [Hz] ΔT
HS
= 18 * 0.523 = 9.4 [°C]
Ripple Frequency F
2
= 15,000 [Hz] T
HS
= Ta + ΔT
HS
Fundamental Voltage V
1
= 310 [V~]
T
HS
= 75 + 9.4 = 84.4 [°C] » OK since hot spot temperature is less than
maximum admitted
Ripple Current I
2
= 7.9 [A] Expected Life at T
HS
= 85°C » 60,000 hours (see lifetime curve)
T
a
= 75°C
I
1
= I(50) = 2 * π * 50 * 10 * 10
−6
* 310 = 0.973 [A]
V
2
= V(15,000) = [7.9/(2 * π * 15,000 * 10 * 10
−6
)] = 8.4 [V]