IEC 62848-2:2019

Railway applications - DC surge arresters and voltage limiting devices - Part 2: Voltage limiting devices

IEC 62848-2:2019 applies to Voltage Limiting Devices (VLDs) to be applied in DC traction systems in order to comply with protective provisions against electric shock from DC, and combined AC – DC voltages, in accordance with the IEC 62128 series, taking into account stray current provisions.
VLDs operate in such a way as to connect the track return circuit of DC railway systems to the earthing system or to conductive parts within the overhead contact line zone or current collector zone.

General Information

• Status: Published
• Publication Date: 17-Jun-2019
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 45.060.01 - Railway rolling stock in general
• Technical Committee: TC 9 - Electrical equipment and systems for railways
• Drafting Committee: PT 62848-2 - TC 9/PT 62848-2
• Current Stage: PPUB - Publication issued
• Start Date: 31-May-2019
• Completion Date: 18-Jun-2019

Standards Content (Sample)

IEC 62848-2 ®
Edition 1.0 2019-06
INTERNATIONAL
STANDARD
Railway applications – DC surge arresters and voltage limiting devices –
Part 2: Voltage limiting devices

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IEC 62848-2 ®
Edition 1.0 2019-06
INTERNATIONAL
STANDARD
Railway applications – DC surge arresters and voltage limiting devices –

Part 2: Voltage limiting devices

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 45.060.01 ISBN 978-2-8322-6884-1

– 2 – IEC 62848-2:2019 © IEC 2019
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Classes of VLD . 9
5 Characteristics and requirements of the VLDs . 10
5.1 Marking . 10
5.2 Service requirements . 11
5.2.1 Normal outdoor service conditions . 11
5.2.2 Normal indoor service conditions . 11
5.2.3 Abnormal service conditions . 11
5.3 General characteristics . 12
5.4 Minimum requirements . 12
5.4.1 Response time . 12
5.4.2 Additional requirements for VLDs of Class 1 . 12
5.4.3 Additional requirements for VLDs of Classes 3 and 4 . 12
5.5 Electrical characteristics and thermal rating . 12
5.6 Protection of VLDs against lightning. 13
5.7 Command and control (Classes 3 and 4 only) . 13
5.7.1 Local control . 13
5.7.2 Remote signalling . 13
5.7.3 Operation and alarm recordings . 14
6 Type tests . 14
6.1 General . 14
6.2 Nominal triggering voltage U and non-triggering voltage U . 15
Tn W
6.2.1 Procedure for welding shut spark gap VLDs (Class 1) . 15
6.2.2 Procedure for thyristor type VLDs (Class2) . 16
6.2.3 Procedure for mechanical switching VLDs and for combined thyristors
with mechanical switching devices VLDs (Class 3 and Class 4) . 17
6.3 Leakage current . 17
6.4 DC current withstand . 18
6.4.1 General . 18
6.4.2 DC rated current test . 18
6.4.3 Short time withstand current test . 19
6.5 AC current withstand characteristics (optional). 20
6.6 Response time characteristics . 20
6.6.1 Response time for DC voltage . 20
6.6.2 Response time for combined AC-DC voltage . 22
6.7 Lightning current impulse withstand characteristics for VLDs exposed to
direct lightning strikes . 24
6.8 Recovery voltage test (Classes 3, 4) . 25
6.9 Reverse voltage test (Class 2.1) . 26
6.10 Dielectric tests for panel type voltage limiting devices (Classes 3 and 4) . 27
6.10.1 Test conditions . 27
6.10.2 Power-frequency voltage withstand test . 27
6.11 Degree of protection of enclosures. 27
6.12 Environmental tests for outdoor equipment . 28

6.13 Determination of minimum current for safe short circuiting of Class 1 VLDs . 28
7 Routine tests . 29
7.1 General . 29
7.2 VLDs of Classes 3 and 4 . 29
7.3 Dielectric tests for panel type voltage limiting devices . 29
Annex A (informative) Preferred ranges of the principal properties of the VLDs. 30
Bibliography . 34

Figure 1 – Test circuit for testing of response time . 21
Figure 2 – T evaluation . 22
R
Figure 3 – Response time characteristic . 22
Figure 4 – Test circuit for testing of response time T for combined AC-DC voltage . 24
R
Figure 5 – Evaluation of response time T for combined AC-DC voltage . 24
R
Figure 6 – Circuit for the recovery voltage test . 26

Table 1 – Classes of voltage-limiting device. 10
Table 2 – Type tests . 15
Table 3 – Maximum response time as a function of DC voltages . 20
Table 4 – Response time for combined AC-DC voltages . 23
Table A.1 – Nominal triggering voltage U . 30
Tn
Table A.2 – Instantaneous triggering voltage U . 30
TI
Table A.3 – Rated current I . 30
r
Table A.4 – Short time withstand current I . 31
W
Table A.5 – Leakage current I . 31
L
Table A.6 – Making and breaking capacity . 31
Table A.7 – Lightning current impulse (8/20 µs) I . 31
imp-n
Table A.8 – High current impulse 8/20 μs and 4/10 μs I . 32
imp-high
Table A.9 – High charge impulse I . 32
imp-hc
Table A.10 – Current-time characteristic for safe short circuiting of Class 1 VLDs . 32
Table A.11 – Preferred parameters for high charge impulse I . 32
imp-hc
Table A.12 – Applicable tolerances according to IEC 61643-11:2011 . 33

– 4 – IEC 62848-2:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RAILWAY APPLICATIONS –
DC SURGE ARRESTERS AND VOLTAGE LIMITING DEVICES –

Part 2: Voltage limiting devices

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