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AUGUST 1999 - REVISED FEBRUARY 2005
Specifications are subject to change without notice.
Customers should verify actual device performance in their specific applications.
From 2001, the registrations for FCC equipment changed from the FCC to ACTA, Administrative Council for Terminal Attachments. For this
function, ACTA needed to adopt a US National standard specifying terminal equipment requirements. The TIA, Telecommunications Industry
Association, in conjunction with the EIA, Electronic Industries Alliance, created TIA/EIA-IS-968 for this purpose. The first issue of TIA/EIA-IS-968
is essentially a renumbered version of the FCC Part 68 requirement. Clause and figure changes are shown in the table.
FCC Part 68, ACTA, TIA and EIA
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 values for the TIA/EIA-IS-968 and ITU-T recommendation K.21.
TISP4xxxL3BJ Overvoltage Protector Series
APPLICATIONS INFORMATION
TIA/EIA-IS-968 (FCC Part 68) Impulse Testing
Item
FCC Part 68
Clause 68.302 (b)
Clause 68.302 (c)
Fig. 68.302 (a)
Fig. 68.302 (b)
Fig. 68.302 (c)
TIA/EIA-IS-968
Clause 4.2.2
Clause 4.2.3
Figure 4.1
Figure 4.2
Figure 4.3
Telephone Line Surge – Type A
Telephone Line Surge – Type B
Simplified Surge Generator
Open Circuit voltage Wave shape
Short Circuit Current Wave shape
Standard
Test
Condition
V
Longitudinal
Metallic
Longitudinal
Metallic
Peak
Voltage
V
1500
800
1500
1000
1500
4000
1500
6000
Voltage
Wave Form
μ
s
10/160
10/560
9/720
9/720
Peak
Current
A
200
100
37.5
25
37.5
100
37.5
125
Current
Wave Form
μ
s
10/160
10/560
5/320
5/320
Fictive
Impedance
7.5
8
40
40
TISP4xxxL3
Rating
A
50
30
40
40
Series
Resistance
TIA/EIA-IS-968
(FCC Part 68)
2 x 24
19
0
0
0
10
0
10
ITU-T K.21
Basic Level
ITU-T K.21
Enhanced Level
TIA/EIA-IS-968 terminology for the wave forms produced by the ITU-T recommendation K.21 10/700 impulse generator
Values assume the TISP4xxxL3 is connected inter-conductor and a 400 V primary is used
Transverse
10/700
5/310
40
30
Transverse
10/700
5/310
40
30
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 wave form 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.
For the TIA/EIA-IS-968 10/560 wave form the following values result. The minimum total circuit impedance is 800/30 = 26.7
and the
generator’s fictive impedance is 800/100 = 8
. For an inter-conductor connected TISP4xxxL3, this gives a minimum series resistance value of
26.7 - 8 = 18.7
. After allowing for tolerance, a 20
±
5 % resistor would be suitable. The 10/160 wave form only needs to be considered if
the TISP4350L3 is connected from the conductor to ground. In this case, the conductor series resistance is 24
±
5 % per conductor.
These electrical safety standards for IT (Information Technology) equipment at the customer premise use the IEC (International Electro-
technical Commission) 60950 standard as the core document. The IEC 60950 covers fundamental safety criteria such as creepage and
isolation. The connection to a telecommunication network voltage (TNV) is covered in clause 6.
Europe is harmonized by CENELEC (Comité Européen de Normalization Electro-technique) under EN 60950 (included in the Low Voltage
Directive, CE mark). Up to the end of 2000, the US had UL (Underwriters Laboratories) 1950 and Canada CSA (Canadian Standards Authority)
C22.2 No. 950. The US and Canadian standards include regional changes and additions to the IEC 60950. A major addition is the inclusion of
clause 6.6, power cross withstand containing the flowchart Figure 18b and annex NAC covering testing. Remarks made for UL 1950 will
generally be true for CSA 22.2 No. 950.
IEC 60950, UL 1950/60950, CSA C22.2 No. 950/60950 and EN 60950