What is a SPD (Surge Protection Device)?
SPD – Surge Protection Device
An SPD (Surge Protection Device) is a safety device found in electrical panels that protects equipment from voltage surges.
- Lightning,
- Utility switching,
- Poor wiring or
- Turning ON and OFF of significant motor loads
can all cause surges.
What is a Transient Overvoltage?
Transient overvoltages are short-duration electrical surges caused by the rapid release of previously stored energy or by other sources.
Transient overvoltages can occur naturally or be caused by humans.
How can Transient Overvoltage occur?
Man-made transients are caused by the switching of motors & transformers, as well as certain types of lighting.
Actually, this was not an issue in domestic installations but with the introduction of advanced technologies such as
- Electric vehicle charging,
- Air/ground source heat pumps and
- Speed-controlled washing machines
transients have become much more common.
Natural transient overvoltages occur as a result of indirect lightning strikes most commonly caused by a direct lightning strike on an adjacent overhead power (or) telephone line causing the transient overvoltage to travel along the lines and cause significant damage to the electrical installation along with equipment.
What does an SPD do?
An SPD provides protection for electrical and electronic equipment by:
1). Absorbs or redirects excess voltage prior to it reaches the components.
2). Protects sensitive equipment such as servers, CCTV, BMS, medical devices and household appliances.
3). Reduces downtime and avoids equipment burnout.
How does SPD Work?
When a surge occurs:
Voltage suddenly rises above usual levels.
SPD transfers the excess energy to the earthing system.
The voltage provided to the equipment remains within a safe range.
SPD Indicators:
The majority of SPDs have
Green: SPD Healthy / Operational
Red: SPD Fault / Replace SPD module
Earthing Requirement:
SPD performance depends largely on good earthing.
Low earth resistance (usually less than 1-2 ohms for sensitive facilities).
Poor earth equals ineffective SPD.
SPD Standard
IEC 61643-1
EN/IEC 61643-11
IEC 61643-11/2011
Where is SPD installed?
SPDs are deliberately placed at several points throughout the electrical installation to provide layered safety:
1). Main Distribution Board (MDB) – Main Distribution Board (MDB) provides primary protection.
2). Sub-Distribution Boards (SDBs) – Sub-Distribution Boards (SDBs) provide secondary protection.
3). Sensitive Loads – Near sensitive loads provides final protection at the equipment level.
Precautions when installing SPD
SPDs cannot provide adequate surge protection unless they are properly installed.
1). When installing a surge protector take the following precautions:
2). To divert surge current away from sensitive equipment the SPD must be mounted in parallel with circuits or devices.
3). Connecting wire lengths for the SPD in switchboard shouldn’t exceed 0.5 meters.
4). Using a Type 1 surge protector alone may not be sufficient for properly discharging high-energy currents & limiting overvoltages. It is advised to add a Type 2 (or) Type 3 surge protector.
5). All installation work must be completed by certified electricians in accordance with the local electrical codes to guarantee correct grounding and unit mounting.
Types of SPD
Different types of SPD are:
- Type 1 SPD
- Type 2 SPD
- Type 3 SPD
Type 1 SPD
Installed at the building’s main entrance.
Withstands direct lightning damage.
Used in structures equipped with exterior lightning protection.
Type 2 SPD
Installed on distribution boards.
It protects against indirect and switching surges.
Type 3 SPD
Installed nearby sensitive equipment (final circuits).
Used as an extra layer of protection.
Advantages of using SPD
1). SPD prevents equipment damage.
2). SPD extends the lifespan of gadgets.
3). SPD improves the reliability of facility operations.
4). SPD reduces maintenance costs.
Conclusion
The Surge Protector is the actual protective device protecting your electrical system and expanding equipment life.
The SPD protects against severe, dangerous power surges effortlessly even in basic instruments with small, delicate electronic components.