AN1172

Resistive loads on/off control

11/23

To avoid destroying the ACSs at each lamp flashover, a power resistor can be added in

series with the light.

half sinus conduction). R is calculated as following:

Equation 6

The power dissipated by the resistor is linked on the load RMS current, and so on the load

Equation 7

A 33

Ω 1/2 W resistor is sufficient.

Figure 11. gives the overcurrent measured with such a resistor during the flashover of a

25 W light bulb.

Figure 11.

Flashover current limited by a 33

Ω 1/2 W resistor

Ω

=

=33

10

2

230

R

W

39

.

0

230

/

25

33

V

/

P

R

P

2

2

L

=

×

=

⋅

=

Iout (2 A/div)