Board performances

UM0575

10/20

mains, as described in the IEC 61000-4-5 standard, when the e-STARTER is off, two cases

can occur:

●

A no-run capacitor is connected across the e-STARTER: the surge voltage is then

entirely held by the ACST6. If the energy is high enough, the leakage current of the

device can exceed its break-over level, leading to a turn-on of the e-STARTER lasting

at worst 10 ms (refer to Figure 9).

●

A run capacitor is used: the surge energy is absorbed by this capacitor. The voltage

level is then limited below 1 kV, which is the typical clamping level of the ACST6. No

spurious turn-on occurs in this case (refer to Figure 10).

It should be noted that in case of a spurious triggering in break-over mode, the ACST6

current is limited by the START winding inductance. The current value is then typically in the

range of 2 A. This is far below the level guaranteed with ACST6, where a 47

Ω load can be

used in such operation mode (refer to the ACST6 datasheet). With a 2 kV surge, the peak

current then equals 40 A in this case.

2.5

Reliability and safety

Reliability tests have been performed with ACST6-7ST samples submitted to a current

shape equivalent to an inrush current of 11 A RMS during 0.5 s. No parameter evolution of

these samples has been detected after 450,000 cycles, which is representative of the

lifetime of a refrigerator. This result demonstrates the excellent capability of these 6 A

products even for applications with high inrush currents.

Concerning safety, the EN6033561 standard imposes the consideration of short-circuit or

diode-mode failures of all silicon power switches involved in safety features. The failure of an

entire e-STARTER cannot lead to safety issues (electrical or mechanical shock, fire). If the

e-STARTER power switch dies in short-circuit or diode-mode, the start winding current is still

limited by the PTC. The start winding is then protected and the compressor still works.

Indeed, the starter function is still ensured by the PTC. The only drawback is that the

standby losses increase back to 2.5 W.

Figure 9.

Spurious e-STARTER triggering

with a 2 kV surge (230 V

compressor)

Figure 10.

e-STARTER voltage limited to 648 V

thanks to the RUN capacitor (2 kV

IEC61000-4-5 surge)

AM00905v1

+ 648 V

VAK

VMAINS

IA

+ 648 V

VAK

VMAINS

IA

AM00906v1