SH/T 3164-2021Design specification for instrument system lightning surge protection in petrochemical industry (English PDF)

3.1 Terms

For the purposes of this document, the following terms and definitions apply.

3.1.1 air-termination system

Metal objects and metal structures used to directly receive or withstand lightning strikes, such as. lightning rods (formerly known as lightning rods), lightning strips (wires), lightning nets, etc.

3.1.5 bonding

Connect equipment, instruments, earthing busbars, etc. that need to be earthed with earthing wires and bonding conductors to form a earthing system.

3.1.6 bonding conductor

A conductor that is used to connect various equipment that need to be earthed, various bonding bars, etc., to form a earthing system.

3.1.11 lightning electromagnetic induction

The phenomenon that the lightning current generates an electromagnetic field in the surrounding space and the conductor in this electromagnetic field generates an induced electromotive force.

3.1.12 electromagnetic shielding

A barrier to the protected target with materials that can reduce the passage of electromagnetic fields.

3.1.13 lightning surge

The pulse-shaped current and voltage generated by lightning electromagnetic induction and conducted along a circuit or conductor. It is also called lightning surging.

3.1.14 equipotential bonding

Use conductors to conductively connect various metal components, metal facilities, metal pipes, metal equipment, etc., so that the potential of each object is approximately equal.

3.1.27 safety extra-low voltage

The voltage that electrical insulation and isolation from other power systems, voltage does not exceed the limit. <= AC 50V, or <= DC 120V, exposed conductive parts are not earthed, in compliance with GB/T 16895.21-2020/IEC 60364-4-41.2017 on safety extra-low voltage specified voltage.

3.2 Abbreviations

The following abbreviations apply to this Specification.

4.3 The protective earthing, working earthing, intrinsic safety earthing, shielding

earthing, anti-static earthing, and surge protective device earthing of the instrument shall finally be connected to the electrical earth termination system. The earth resistance shall comply with the earth resistance of the electrical earth termination system.

5.1 The implementation of lightning surge protection engineering for instrumentation

shall be determined based on one of the conditions of 5.2 to 5.6.

Abbreviation Full English name

5.4 When the regulatory authorities or owners assess that the possible economic losses

caused by lightning strikes are greater than the tolerable economic losses, or the expected risks of lightning strikes are greater than the tolerable risks, lightning surge protection engineering for instrumentation shall be implemented.

5.5 When the number of lightning strikes with lightning current intensity above 130kA

has occurred in the factory area >= 2 times/year, it is appropriate to implement lightning surge protection engineering for instrumentation.

5.6 Departments with corresponding management or supervision rights may implement lightning surge protection engineering for instrumentation in accordance with regulations without evaluation.

6.1 Instrumentation earthing system in control room

6.1.1 The instrument earthing system in the control room shall adopt a mesh-structured earthing system, which can be used in various buildings and rooms equipped with instruments.

6.1.5 For single-row cabinets or single-row consoles, a single bonding bar shall be used.

6.1.6 The bonding bar of the mesh structure shall be made of copper or hot-dip galvanized flat steel welded with a cross-sectional area of >=40 mm × 4 mm (width × thickness). There shall be no wire connections between bonding bar materials.

6.1.7 The bonding bar of the mesh structure shall be installed on the bottom support of the cabinet or other brackets. The height shall be close to the bottom of the cabinet, see

Appendix A. The bonding bar shall be installed using non-insulating brackets and other materials.

6.1.12 The earth wire (PE wire) from the power supply system shall be connected to the bonding bar of the instrument distribution cabinet. Multi-stranded copper core wires with a cross-sectional area of >=16 mm2 shall be connected to the mesh structure bonding bar by crimping.

6.2 Cabinet and operating console earthing

6.2.1 The working earthing and protective earthing in the cabinet shall be directly connected to the nearest bonding bar below according to the earthing diagram in Figure

6.2.4 Copper or hot-dip galvanized flat steel with a cross-sectional area of >=40mm ×

4mm (width × thickness) shall be laid as a bonding bar along the power supply cable path for instruments, operating equipment, and metal operating desks that need to be earthed. Metal operating consoles equipped with equipment that require external earthing shall be connected to the nearest bonding bar according to Figure 6.2.4.

6.2.5 Every instrument, equipment, instrument panel, operating console, etc. that needs

to be earthed shall be connected to a mesh-type bonding bar using a earthing wire. The number of series connections required shall be <=3.The cabinet shall not be earthed in a chained series manner connected by wires.

6.3 Bonding conductor and wire

6.6 Earthing sign

6.6.1 The construction of various earthing wires, bonding conductors, bonding bars, etc.

in the control room shall be easy to inspect and maintain. Visible signs shall be set up.

6.6.2 The connection to the bonding terminal shall be clearly marked.

7.1 General

7.1.1 Surge protective devices shall be maintenance-free. They shall be able to withstand multiple lightning surges without being damaged.

7.1.4 When the instrument needs to be equipped with a surge protective device, it shall be configured according to the provisions of 7.2, 7.3, and 7.4.

7.1.5 Surge protective devices with monitoring functions can be used and corresponding centralized monitoring equipment can be configured.

7.2 Type of surge protective device

7.2.1 Commonly used surge protective devices for instruments include. signal type, DC

24V power supply type, AC or DC 220V power supply type, communication type, etc.

The selection shall be determined based on factors such as protection purpose, signal type, operating voltage level, installation location, and installation method.

7.2.5 The control system communication network shall be equipped with surge protective devices according to the communication category. Specifications and parameters shall be suitable for the connected communication equipment.

7.2.6 Surge protective devices with multiple signal channels shall not be used. For four- wire instruments powered by DC 24V, since the supply current value is similar to the signal current value, the power supply line is regarded as a signal channel, and a dual signal channel surge protective device can be used.

7.3 Parameters of surge protective device for signal type

The basic parameters of surge protective device for signal type shall comply with the requirements in Table 7.3.

7.5.2 For on-site AC power supply instruments that need to be equipped with surge protective devices, surge protective devices shall be equipped according to the AC power supply parameters.

8.1 Shielding for instrumentation in control room

8.2 Installation for surge protective device

8.2.1 Control room instrumentation shall be equipped with surge protective devices as specified in Chapter 7.

8.2.2 Control room instrument surge protective devices shall be installed in the cabinet.

8.2.3 After the instrument cable enters the control room, it shall be connected to a surge protective device first, and then to subsequent instruments (including fuse terminals).

8.3 Earthing and bonding for surge protective device

9.1 Lightning protection for field instrumentation

9.2 Installation for surge protective device

9.2.1 Field instruments shall use fabricated surge protective devices. For instruments where fabricated surge protective devices cannot be installed, built-in surge protective devices can be used. The parameters of the surge protective device shall comply with the provisions of 7.3.Field instruments shall use line-line protection surge protective devices.

9.3 Field instrumentation earthing

9.3.1 The earthing of field instruments shall be protective earthing. It shall comply with the requirements of Table 9.3.1.The enclosure earthing terminal or natural earthing through installation shall be used.

9.3.4 The earth wire of the surge protective device shall be connected to the earth terminal inside the instrument. At the same time, the earth terminal of the instrument housing shall be earthed.

9.3.5 Instruments, equipment, instrument boxes, brackets, etc. that need to be earthed

on site can be connected in series. The number of series connections shall be <=3.

......