T
A
= Ambient temperature > 65 °C
T
max
= 170 °C
The I
max
values specified in the data sheets denote the maximum permissible continuous current
(DC or RMS values for sine-shaped AC) in the temperature range 0 °C to 65 °C.
1.6 Maximum permissible capacitance
The currents during turn-on are much higher than the rated currents during continuous operation.
To test the effects of these current surges EPCOS uses the following standard procedure accord-
ing to IEC 60539-1:
Figure 3
Test circuit for evaluating the maximum permissible capacitance of an NTC thermistor
V
load
Load voltage [V]
C
test
Test capacitance [µF]
R
S
Series resistance [R
S
= 1 Ω]
V
NTC
Voltage drop across the NTC under test [V]
The capacitor C
test
is discharged via the series resistor R
S
and the NTC inrush current limiter. The
load voltage is chosen such that the voltage applied to the thermistor at the start of discharge is
VNTC = 375 V (corresponds to (230 V + ∆V) 2).
Inrush current limiters B57127P0***M301
ICLs P27
Page 7 of 19Please read Cautions and warnings and
Important notes at the end of this document.
