AN2053

Protect against what?

Doc ID 10917 Rev 2

3/15

Figure 4 shows the ITU-T requirement for both the mains induction and contact test circuits.

This simulation is based on the application of 50/60 Hz through resistance during a

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

Figure 4.

ITU-T K20 power induction and power contact surge test definition

Table 1 and 2 show the main worldwide lightning surge standards. Table 1 is dedicated to

classical wired telecom line cards while the Table 2 is dedicated to intra-building

applications. The main worldwide standards for the 50/60 Hz disturbances can be defined

by 2 parameters: the applied voltage, between 60 to 1000 V and the test duration, between

0.2 s to 15 min. This type of disturbances obliges the designer to put series elements, like

PTC or a fuse between line and protection devices.

Section 2 presents the protection concept used to protect both short and long lines.

Table 1.

Main line card lightning surge standards

Country

Standard

Surge

voltage (V)

Waveform

Current (A)

Worldwide

ITU-T K20

1500

10/700 µs

37.5

Worldwide

IEC 61000-4-5

1000/4000

10/700 µs

25/100

Worldwide

IEC 61000-4-5

1000/4000

1.2/50 µs

25/100

USA

GR-1089 Core (Telcordia)

2500

2/10 µs

500

USA

GR-1089 Core (Telcordia)

1000

10/1000 µs

100

Table 2.

GR-1089 Core Intra-building lightning surge standard

Test

Surge Voltage (V)

Waveform

Surge Current per

conductor (A)

Repetitions

Each

polarity

1

±800

2/10 µs

100

1

2

±1500

2/10 µs

100

1

K20 power induction surge generator

Surge

generator

A

B E

R = 600

Ω

R = 600

Ω

Uac

Timing circuit

Equipment

under test

K20 power contact surge generator

A

B E

Uac

Timing circuit

S

T1

T2

10

Ω

10

Ω

160

Ω

160

Ω

600

Ω

600

Ω

Equipment

under test