TISP7125F3, TISP7150F3, TISP7180F3, TISP7240F3, TISP7260F3,
TISP7290F3, TISP7320F3, TISP7350F3, TISP7380F3
TRIPLE BIDIRECTIONAL THYRISTOR OVERVOLTAGE PROTECTORS
MARCH 1994 - REVISED MARCH 2000
times the time constant, which gives 2.75 x 1.88 = 5.15, which is rounded to 5 µs. Thus the short circuit
current rises in 5 µs and decays in 310 µs, giving the 5/310 wave shape.
The series resistance from C to the output is 40 Ω giving an output conductance of 25 A/kV. For each 1 kV of
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capacitor charge voltage, 25 A of output current will result.
For the dual test, the series combination of R plus R and R in parallel (15 + 12.5 = 27.5 Ω) is in shunt with
2
3
4
R . This lowers the discharge resistance from 50 Ω to 17.7 Ω, giving a discharge time constant of 355 µs and
1
a 50% current decay time of 247 µs, which is rounded to 250 µs.
For the rise time, R , R and R are in parallel, reducing the effective source resistance from 15 Ω to 6.82 Ω,
2
3
4
giving a time constant of 1.36 µs, which gives a current rise time of 2.75 x 1.36 = 3.75, which is rounded to
4 µs. Thus the short circuit current rises in 4 µs and decays in 250 µs, giving the 4/250 wave shape.
The series resistance from C to an individual output is 2 x 27.5 = 55 Ω giving an output conductance of
1
18 A/kV. For each 1 kV of capacitor charge voltage, 18 A of output current will result.
At 25 °C these protectors are rated at 70 A for the single terminal pair condition and 95 A for the dual
condition (R and G terminals and T and G terminals). In terms of generator voltage, this gives a maximum
generator setting of 70 x 40 = 2.8 kV for the single condition and 2 x 95 x 27.5 = 5.2 kV for the dual condition.
The higher generator voltage setting for the dual condition is due to the current waveform decay being shorter
at 250 µs compared to the 310 µs value of the single condition.
Other ITU-T recommendations use the 10/700 generator: K.17 (11/88) “Tests on power-fed repeaters using
solid-state devices in order to check the arrangements for protection from external interference” and K.21(10/
96) “Resistibility of subscriber's terminal to overvoltages and overcurrents“, K.30 (03/93) “Positive
temperature coefficient (PTC) thermistors”.
Several IEC publications use the 10/700 generator, common ones are IEC 6100-4-5 (03/95) “Electromagnetic
compatibility (EMC) - Part 4: Testing and measurement techniques - Section 5: Surge immunity test” and IEC
60950 (04/99) “Safety of information technology equipment”.
The IEC 60950 10/700 generator is carried through into other “950” derivatives. Europe is harmonised by
CENELEC (Comité Européen de Normalization Electro-technique) under EN 60950 (included in the Low
Voltage Directive, CE mark). US has UL (Underwriters Laboratories) 1950 and Canada CSA (Canadian
Standards Authority) C22.2 No. 950.
FCC Part 68 “Connection of terminal equipment to the telephone network” (47 CFR 68) uses the 10/700
generator for Type B surge testing. Part 68 defines the open circuit voltage wave shape as 9/720 and the
short circuit current wave shape as 5/320 for a single output. The current wave shape in the dual (longitudinal)
test condition is not defined, but it can be assumed to be 4/250.
Several VDE publications use the 10/700 generator, for example: VDE 0878 Part 200 (12/92)
”Electromagnetic compatibility of information technology equipment and telecommunications equipment;
Immunity of analogue subscriber equipment”.
1.2/50 generators
The 1.2/50 open circuit voltage and 8/20 short circuit current combination generator is defined in IEC 61000-
4-5 (03/95) “Electromagnetic compatibility (EMC) - Part 4: Testing and measurement techniques - Section 5:
Surge immunity test”. This generator has a fictive output resistance of 2 Ω, meaning that dividing the open
circuit output voltage by the short circuit output current gives a value of 2 Ω (500 A/kV).
P R O D U C T
I N F O R M A T I O N
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POINN [ POWER INNOVATIONS LTD ]
