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PQR

Electric shock between electric car-PSD,
Arc accidents and PSD failure cases

1Accident, breakdown
Source : https://news.kbs.co.kr/news/view.do?ncd=2148632
2Electric shock accidents
Source : https://news.kbs.co.kr/news/view.do?ncd=2148632
3Shock voltage test
Source : https://news.kbs.co.kr/news/view.do?ncd=2148632
4Relevant regulations

Enforcement Decree of the Serious Accidents Punishment Act [Enforced 2022.12.8.][Presidential decree No.33023, 2022.12.6., other laws amended]

Enforcement Decree of the Countermeasures Against Natural Disaster Act [Enforced 2023.1.5.][Presidential decree No.33198, 2023.1.3., other laws amended]

Industrial Accident Compensation Insurance Act [Enforced 2023.1.12.][Law No.18753, 2022.1.11., partially amended]

Background of TNC-PQR Series Development

Preventive measures for electric shock accidents caused by
electric car-PSD contact in DC electric railcar line section
1Background

Urban railway in Korea operate Platform Screen Door (PSD) at all stations for the safety of passengers and prevention of fall, and this PSD establishes measures to prevent electrical effect of feed line (railway and pantograph), damages to railroad and pantograph due to electric shock between electric car and platform structure, electrical effect on platform structure in case of short circuit, and electrical shock accidents caused by the contact of passengers due to rail potential increase as the train enters the platform, as well as prevention of malfunction and failure.

2Global technical standard status

1. Korean electric facility regulation (KEC:Korea Electro-technical Code,)

2. EN 50122-1:2022 Railway applications-Fixed installation - Electrical safety, earthing and return circuit

3. EN 50526-2:2014 Railway applications-Fixed installation - D.C surge arresters and voltage limiting devices

3Methodology of electric shock prevention of direct current electric railroad

1. According to KEC, protective measures against electric shock of electric railroad must secure enough space to prevent direct contact of electric train with the live part in addition to live part of the overhead wire in case of nomina voltage direct current of 1.5kv or lower, which must be more than the distance marked in Figure 1.

2. Apply the following when exceeding the reference value in KEC standard or EN standard

(1) Recommend equipotential bonding of PSD and structures with the earth, and insulate the surface firmly

(2) Reinforce structure grounding to reduce rail potential in failure conditions such as ground fault

(3) Apply voltage limiter

(4) Reinforce return wire

(5) Insulate platform podium and structure surface

(6) Reduce trapping time needed to suspend short circuit current

4Study of rail potential and allowed touch voltage standard

Urban railway platforms operate PSD and structures as the safety device to protect passengers from the train when it enters or exits, but the gap between PSD and train may be rather wide in some curvy places, so it is prone to fall or jamming accidents between the train and PSD, and these accidents may result in serious disasters such electrocution and fire accident. Figure 2 displays the rail potential distribution during electric train operation presented in KEC in terms of shock current and touch voltage schematic diagram (Figure 3).

Figure 2
Figure 3
5 Study of correlation between grounding resistance and impedance for equipotential bonding and voltage limit
Figure 2
Figure 3

As seen in Figures 4 and 5, Q(t) and I(t) have higher discharge quantity and shorter discharge duration as R value gets smaller, so (t) reduces significantly at 0.1.

6Study on standards related to protection of direct current electric railway against shock accidents
KEC’s classification of equipotential bonding for shock protection and its subjects

Background of TNC-PQR Series Development

Measures to Prevent Electric Shock Accidents Caused by Contact Between Electric Cars and PSD in DC Catenary Sections

1 Background

[Figure A] System Framework

[Figure B] Functional operation process model

2System implementation and verification
Grounding resistance value : 800 Ω
Grounding resistance value : 5 Ω
Resistance (R) value : 2 Ω
PQR (No ground connection)

Simulations reflecting the conditions of the above R&F Verification Matrix were conducted, including ground resistance values (800Ω, 5Ω), resistance value (2Ω), and Electric Shock Protection Device (ESPD). The results of the surge simulation (voltage: 6kV, 1.2/50μs; current: 3kA, 8/20μs) showed that with a ground resistance value of 800Ω, the current discharge (blue line) did not occur, resulting in a surge voltage (yellow line) of approximately 6kV without attenuation. With a resistance (R) of 2Ω, the discharge attenuated the surge voltage to approximately 3kV. The Electric Shock Protection Device (PQR) demonstrated characteristics of significant current discharge, reducing the surge voltage to approximately 2kV with a very fast discharge time.
* An ideal condition is when the discharge current (blue line) is high, the attenuated voltage (yellow line) is low, and the discharge is rapid.

Background of TNC-PQR Series Development

1
System Functional
Architecture
2Features

Enforcement Decree of the Serious Accidents Punishment Act [Effective 2022.12.8] [Presidential Decree No. 33023, 2022.12.6, Partial Amendment]

Enforcement Decree of the Natural Disaster Countermeasures Act [Effective 2023.1.5] [Presidential Decree No. 33198, 2023.1.3, Partial Amendment]

Industrial Accident Compensation Insurance Act [Effective 2023.1.12] [Act No. 18753, 2022.1.11, Partial Amendment]