Matters to Be Observed When Using This Product

■ Use the noise-preventing capacitor (AC rated voltage type) on the primary power circuit. This capacitor is designed on the

assumption that a 50 Hz or 60 Hz sine wave voltage is applied to the capacitor. When using a capacitor with a DC rated

voltage type in an AC circuit, see "Voltage at Which DC Rated Voltage Type Capacitor Can be Used in AC Circuit.

" Do not use this type of capacitor on the primary power circuit.

■ When a capacitor is used at a high frequency, its self-heating poses a risk of thermal runaway (smoke generation, ignition).

Reduce the working voltage according to the example shown below. For capacitors used at a high frequency,

we recommend ECHU(X)/(C), ECWF(A)/(L), and ECWH(A)/(C)/(V).

<Example of working voltage reduction>

Capacitor: ECWF2154JA (250 V DC, 0.15 μF) Working frequency: 40 kHz (sine wave)

Allowable current value (entered in the delivery specification sheet): 2.0 Arms at 40 kHz

According to the above equation, the AC working voltage (50 Hz or 60 Hz sine wave voltage) of ECWF(A) operating

at 40 kHz and 53 Vrms is calculated at 125 Vrms. This indicates that using ECWF(A) at a high frequency causes

its allowable voltage to drop. Note that this equation cannot be applied to a working voltage not in a sine waveform,

in which case please contact with us.

■ Make sure that the peak value of a pulse voltage (Vo-p) applied across both ends of the capacitor is equal to or lower

than the rated DC voltage. When the capacitor is used at a high frequency, its self-heating impairs the voltage

endurance characteristics and may lead to destruction of the capacitor. Measure the self-temperature rise value of

the capacitor and keep it equal to or lower than the specified value.

■ When a voltage higher than the rated voltage (allowable voltage) is applied to the capacitor as a result of unusual circuit

behavior caused by a failure of a different component, provide the capacitor with a means of safety protection.

■ Because of its low internal impedance, the capacitor carries an extremely large current flow, depending on the circuit

in which the capacitor is incorporated. Particularly, a high pulse current could flow through the capacitor when the

power supply is turned on or off. Make sure to check whether a high pulse current is flowing through the capacitor.

When the capacitor is used in a high-frequency circuit, such as an inverter circuit and switching circuit, a large current

may flow through the capacitor. Be careful in such cases.

■ A current flow exceeding the allowable current value may put the capacitor in a low-capacitance or open state or cause

the capacitor to generate heat. This may result in degraded voltage endurance performance or short circuit, thus leading

to smoke generation, ignition, etc. When using the capacitor, keep a capacitor current and temperature equal to or

lower than the allowable current value and self-temperature rise value specified in the delivery specification sheet.

■ It is necessary that the allowable current in breakdown mode be examined in terms of both pulse current (peak current)

and continuous current (RMS current). Confirm that both pulse current and continuous current are equal to or lower

than the allowable current value and then use the capacitor.

■ The frequency characteristics of the loss tangent (tanδ) of a capacitor vary depending on the type of a dielectric material

used. For this reason, a different allowable RMS current for a given working frequency shows depending on the product

type. When a capacitor is used at a high frequency, in particular, its loss tangent (tanδ) gets larger, a current flow

larger than the RMS current causes the capacitor to thermally runaway, which may lead to smoke generation or

ignition. Using the capacitor at a high frequency, therefore, requires special caution.

Please let us know the operating conditions for the capacitor to give you detailed advice.

Otherwise, keep the self-temperature rise value and surface temperature of the capacitor within the allowable range even

in the most unfavorable operation conditions.

23-Apr-25

　 Circuit design (working current)

V =

=

= 53 Vrms

2.0

2

×3.14×40×103×0.15×10-6

I

2πfC