MARCH 1999 - REVISED FEBRUARY 2005

Specifications are subject to change without notice.

Customers should verify actual device performance in their specific applications.

Deployment

TISP7xxxH3SL Overvoltage Protector Series

APPLICATIONS INFORMATION

Impulse Testing

These devices are three terminal overvoltage protectors. They limit the voltage between three points in the circuit. Typically, this would be the

two line conductors and protective ground (Figure 11).

In Figure 11, protectors Th2 and Th3 limit the maximum voltage between each conductor and ground to the ±V(BO) of the individual protector.

Protector Th1 limits the maximum voltage between the two conductors to its ±V(BO) value.

Manufacturers are being increasingly required to design in protection coordination. This means that each protector is operated at its design

level and currents are diverted through the appropriate protector, e.g. the primary level current through the primary protector and lower levels

of current may be diverted through the secondary or inherent equipment protection. Without coordination, primary level currents could pass

through the equipment only designed to pass secondary level currents. To ensure coordination happens with fixed voltage protectors, some

resistance is normally used between the primary and secondary protection. The values given in this data sheet apply to a 400 V (d.c.

sparkover) gas discharge tube primary protector and the appropriate test voltage when the equipment is tested with a primary protector.

To verify the withstand capability and safety of the equipment, standards require that the equipment is tested with various impulse wave forms.

The table below shows some common values.

If the impulse generator current exceeds the protector’s current rating, then a series resistance can be used to reduce the current to the

protector’s rated value to prevent possible failure. The required value of series resistance for a given waveform is given by the following

calculations. First, the minimum total circuit impedance is found by dividing the impulse generator’s peak voltage by the protector’s rated

current. The impulse generator’s fictive impedance (generator’s peak voltage divided by peak short circuit current) is then subtracted from the

minimum total circuit impedance to give the required value of series resistance. In some cases, the equipment will require verification over a

temperature range. By using the rated waveform values from Figure 10, the appropriate series resistor value can be calculated for ambient

temperatures in the range of -40 °C to 85 °C.

Figure 11. MULTI- POINT PROTECTION

Th3

Th2

Th1

Standard

Peak Voltage

Setting

V

Voltage

Waveform

µs

Peak Current

Value

A

Current

Waveform

µs

TISP7xxxH3

25 °C Rating

A

Ω

Series

Resistance

Coordination

Resistance

(Min.)

GR-1089-CORE

2500

2/10

500

2/10

500

0NA

1000

10/1000

100

10/1000

100

FCC Part 68

(March 1998)

1500

10/160

200

10/160

250

0NA

800

10/560

100

10/560

130

1000

1500

1500

9/720 †

(SINGLE)

(DUAL)

25

37.5

2 x 27

5/320 †

5/320 †

4/250

200

200

2 x 225

I 31-24

1500

0.5/700

37.5

0.2/310

200

0

NA

ITU-T K.20/K.21

1000

1500

4000

4000

10/700

(SINGLE)

(SINGLE)

(DUAL)

25

37.5

100

2 x 72

5/310

5/310

5/310

4/250

200

200

200

2 x 225

0

NA

NA

4.5

6.0

† FCC Part 68 terminology for the waveforms produced by the ITU-T recommendation K.21 10/700 impulse generator

NA = Not Applicable, primary protection removed or not specified.