TISP7xxxF3 (MV, HV) Overvoltage Protector Series
APPLICATIONS INFORMATION
Deployment
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 32).
Th3
Th1
Th2
Figure 32. MULTI-POINT PROTECTION
In Figure 32, protective functions Th2 and Th3 limit the maximum voltage between each conductor and ground to their respective ±V
(BO)
values. Protective function Th1 limits the maximum voltage between the two conductors to its ±V
value.
(BO)
Lightning Surge
Wave Shape Notation
Most lightning tests, used for equipment verification, specify a unidirectional sawtooth waveform which has an exponential rise and an
exponential decay. Wave shapes are classified in terms of rise time in microseconds and a decay time in microseconds to 50 % of the maximum
amplitude. The notation used for the wave shape is rise time/decay time, without the microseconds quantity and the “/” between the two values
has no mathematical significance. A 50 A, 5/310 waveform would have a peak current value of 50 A, a rise time of 5 µs and a decay time of
®
310 µs. The TISP surge current graph comprehends the wave shapes of commonly used surges.
Generators
There are three categories of surge generator type: single wave shape, combination wave shape and circuit defined. Single wave shape
generators have essentially the same wave shape for the open circuit voltage and short circuit current (e.g. 10/1000 open circuit voltage and
short circuit current). Combination generators have two wave shapes, one for the open circuit voltage and the other for the short circuit current
(e.g. 1.2/50 open circuit voltage and 8/20 short circuit current). Circuit specified generators usually equate to a combination generator,
although typically only the open circuit voltage wave shape is referenced (e.g. a 10/700 open circuit voltage generator typically produces a 5/
310 short circuit current). If the combination or circuit defined generators operate into a finite resistance, the wave shape produced is interme-
diate between the open circuit and short circuit values.
ITU-T 10/700 Generator
This circuit defined generator is specified in many standards. The descriptions and values are not consistent between standards and it is
important to realize that it is always the same generator being used.
Figure 33 shows the 10/700 generator circuit defined in ITU-T recommendation K.20 (10/96) “Resistibility of telecommunication switching
equipment to overvoltages and overcurrents”. The basic generator comprises of:
Capacitor C , charged to voltage V , which is the energy storage element
1
C
Switch SW to discharge the capacitor into the output shaping network
Shunt resistor R , series resistor R and shunt capacitor C form the output shaping network
1
2
2
Series feed resistor R to connect to one line conductor for single surge
3
Series feed resistor R to connect to the other line conductor for dual surging
4
In the normal single surge equipment test configuration, the unsurged line is grounded. This is shown by the dotted lines in the top drawing of
Figure 33. However, doing this at device test places one terminal pair in parallel with another terminal pair. To check the individual terminal
pairs of the TISP7xxxF3, without any paralleled operation, the unsurged terminal is left unconnected.
MARCH 1994 - REVISED MARCH 2006
Specifications are subject to change without notice.
Customers should verify actual device performance in their specific applications.
BOURNS [ BOURNS ELECTRONIC SOLUTIONS ]
