Surge Protection Devices for maintaining power surges in electrical units

This article briefly discusses the technical performance of Surge Protection Devices (SPDs) in controlling and minimising the power surge instances and their following damages that can potentially hamper the electrical unit’s performance.

Surge Protection Devices (SPD) are one of the critical components for an electrical installation to protect the electrical unit, consisting of a consumer unit and wiring accessories, from any potential power surges, also known as overvoltage. It also protects the electrical equipment and electronic accessories from any damage caused by a power surge.

Market trends for Surge Protection Devices (SPDs)

If suitable, a surge protection device can be installed in an existing consumer unit, and the desired space is available or allocated. An electrical surge can either result in an instant failure or damage to the equipment that is only evident over a while.

The use of electronic equipment is increasing in manufacturing facilities, corporations, and the residential sector, and the need for power-quality protection equipment is becoming essential. Surge protection for the entire facility and individual equipment is gaining significance as transient voltages, and surges can impact productivity and profitability.

On this note, Mukesh Thakur, Manager- Marketing, Finder India Pvt. Ltd., says, “The surge protection devices market is growing significantly due to the growing demand for protection systems for electronic devices, power quality issues, a rise in alternative energy programs, and cost escalation due to frequent equipment failures.” “The plug-in SPD segment is expected to constitute the largest market share in the coming years.”

Brijesh Malik, Vice President, Dehn India (P) Limited, describes the types of Surge Protection Devices, saying, more use of Type 1 based Surge Protection Devices for Main’s LT/Meter Panel level with higher short-circuit ratings up to 65/100KArms, coordinating with Main’s Switchgear ratings. Type 1 SPDs for signal and data lines, PV Inverters (String / Central) and SMB boxes.

Minimising over-voltage surge instances in electrical/power systems

SPD is designed to limit transient over-voltages by creating a potential equalisation concerning the normal mode and standard mode circuits to limit the amplitude of this overvoltage to a value that is not hazardous for the electrical installations or control systems.

Mukesh highlights that most SPDs include MOVs and GDTs as the main components for clamping the surges. Metal Oxide Varistors (MOV) have the property of maintaining a relatively small voltage change across their terminals while the surge current flowing through them varies over several orders of magnitude. This nonlinear action allows them to divert the current of a surge when connected in parallel across the line. A gas discharge tube is a sealed glass-enclosed device containing a special gas mixture trapped between two electrodes, which conduct electric current after becoming ionised by a high voltage spike. GDTs have extremely high pulse ratings for their size. They are designed for use over a broad voltage spectrum.

On the other hand, Brijesh shared a brief on ensuring system safety with Type 1 and 2 SPDs. When installed in an electrical power system, these SPDs ensure the safety and protection of downstream equipment from lightning (10/350sec) and switching surges (8/20sec).” Moreover, the installed SPDs in the system safely discharge lightning and surge current to the ground and thus improve uptime and 24×7 availability of the power system,” he adds.

Types of surges are addressed through SPDs.

“Surges of atmospheric origin like direct lightning strikes, switching surges generated due to switching action of various resistive, inductive, and capacitive loads, and electrostatic discharge surges are mainly addressed with SPDs,” says Mukesh.

SPD is divided into three types depending on the surge limiting characteristics. A 10/350 s current wave is characterised by a 10/350 μs current wave. A Type 2 SPD is characterised by an 8/20 μs current wave. Type 3 SPD is characterised by a combination of voltage waves (1.2/50 μs) and current waves (8/20 μs).

Under lightning protection level (LPL) – I, type 1-rated SPDs can safely discharge lightning of 10/350sec up to 100KA.

SPDs rated type 2 can discharge surges of 8/20sec up to 40KA.

SPDs with a Type 3 rating can discharge surges of up to 5KA for 8/20sec.

Maintaining efficiency in SPDs.

It is always important to design the SPD with technology and characteristics appropriate for Indian requirements. The grounding and maintenance practices, as well as the variations in power supply conditions in different parts of the country, need a worst-case scenario to be envisaged based on which a special Rated Voltage for the surge protection devices is to be considered.

Commenting more on it, Mukesh explains that the lightning strike density of India is also a critical factor in selecting the SPDs concerning the other parameters like the surge current waveform and amplitude. Further, the other significant specifications to be considered are the nominal and threshold voltages, response time, ambient temperature withstand range, etc., which are some of the critical factors to consider for maintaining efficiency in SPDs. 

SPDs are generally defined in terms of the type of technology, i.e. Metal Encapsulated Spark Gap, Metal Oxide Varistors (MOVs), GD tubes, and Zener diodes. “Major parameters for proper selection of SPDs are lightning current and surge discharge capabilities, short-circuit limiting and extinguishing, low voltage protection level and low let-through-energy to protect terminal equipment, continuous monitoring via local mechanical flag-based indication; and potential-free contacts (NO/NC) for remote indications,” says Brijesh.

DEHN provides metal-encapsulated Spark Gap-based Type 1 SPD for 230/400 V AC power supplies with an inbuilt fuse for safe disconnection during a fault condition, short-circuit extinction capabilities up to 100KArms suitable for higher transformer ratings up to 5MVA, low voltage protection level up to 1.5KV to protect terminal/downstream equipment, local flag based and remote indication for continuous health monitoring, and a KEMA tested solution.

Dehn’s Type 2 SPDs for low voltage power supply systems are leakage current solutions with a combination of the spark gap and MOV for longer life, surge discharge capabilities up to 80KA, low voltage protection level up to 1.5KV to protect terminal/downstream equipment, local and remote indications for continuous health monitoring, and a KEMA tested solution.

Finder India offers Type 1+2, Type 2, and Type 3 SPDs complying with EN/IEC 61643 for AC and DC power lines up to 1500V applications. The SPDs have an improved maximum operating voltage range and inbuilt diagnostic features like visual flag indication of SPD healthy/replacement status and contact for remote signalling of SPD status. The SPDs are suitable to handle both lightning impulse current (10/350 micro-seconds) (Iimp) and nominal discharge current (8/20 micro-seconds) (In).

A new range of SPDs is now available for photovoltaic applications, electric vehicle chargers, street light protection per Indian conditions, Ethernet line protection for IT infrastructure and CCTV cameras used in smart city applications. Digital and analogue signal line SPDs are now available with features of pluggability. FINDER team can customise the solutions, which can also be suitable for particular unique applications.

The plug-in SPD segment is expected to constitute the largest market share in the coming years.
Mukesh Thakur, Manager Marketing, Finder India Pvt. Ltd.

The system’s SPDs safely discharge lightning and surge current to the ground, improving uptime and 24×7 availability.
Brijesh Malik, Vice President, Dehn India (P) Limited