Telecom disturbances

AN2266

4/16

DocID11830 Rev 2

Figure 4. ITU-T K20 lightning surge test definition

The applied peak voltage is 1.5 kV (10/700 µs - Enhanced level) which corresponds to an

applied peak current of 37.5 A (5/310 µs). Five applications of each polarity have to be

performed. These tests must be managed in both metallic and longitudinal modes (see

- “the equipment shall continue to operate properly after the test”.

Figure 5 gives the ITU-T K20 requirements for both power induction and contact test

circuits. This simulation is based on the application of 50/60 Hz through a resistor during a

programmed duration (i.e. 0.2 s for induction and 15 min. for contact).

Figure 5. ITU-T K20 power induction and power contact surge test definition

The applied rms voltage for the power induction test is 600 V which corresponds to an

applied rms current of 1 A. The duration of the test is 0.2 s and five applications have to be

performed. This test must bemanaged in both metallic and longitudinal modes. The

standard defines the acceptance criterion as A - “the equipment shall continue to operate

properly after the test”.

The applied rms voltage for the power contact tests is 230 V. The applied rms current

depends on the resistor used (10, 20, 40, 80, 160, 300, 600 and 1000

Ω). The duration of

the test is 15 min. and only one application has to be performed. This test must be managed

in both metallic and longitudinal modes. The standard defines the acceptance criterion as A

- “the equipment shall continue to operate properly after the test” for 160, 300 and 600

Ω

(Enhanced level) and as B - “the equipment may be damaged but should not become a fire

or electrical hazard”, for the other resistors.

U

20 µF

R1 = 50

Ω

R2 = 15

Ω

0.2 µF

K20 lightning

generator

R3 = 25

Ω

Coupling

network

Equipment

under test

E

B

A

R3 = 25

Ω

Coupling

network

Equipment

under test

E

B

A

R4 = 25

Ω

K20 lightning

generator

A. K20 Lightning generator

C. K20 Longitudinal test

B. K20 Metallic test

20

Ω

Equipment

under test

A

B E

10

Ω

Uac

Timing

circuit

100

Ω

20

Ω

10

Ω

100

Ω

S

T

T

A. K20 power induction generator

R = 600

Ω

Equipment

under test

A

B E

R = 600

Ω

Uac

Timing circuit

B. K20 power contact generator