Solution Summary: Surge Protection Device (SPD)
Surge protection devices can be considered as engineering controls due to their ability to prevent voltage spikes that can damage equipment and electrocute people. The Hierarchy of Control (HOC) is a well-known framework to evaluate the performance of safety solutions in Occupational Safety and Health (OSH) research (Wakefield et al. 2014). HOC consists of five levels of effectiveness: (1) Elimination, (2) Substitution, (3) Engineering Controls, (4) Administrative Controls, (5) Personal Protective Equipment; with elimination being the most effective. At the third level, engineering controls “use safeguarding technology to place a barrier to keep a hazard from reaching workers” (Zhao et al. 2015).
The Surge Protection Device (SPD) is a component of the electrical installation protection system (The Surge Protection Device [SPD] 2013), designed to protect electrical devices from voltage spikes (short duration electrical transients in voltage in an electrical circuit) while blocking voltage over a safe threshold. When a threshold is over the safe voltage (usually 120V), a surge protector shorts to ground voltage or blocks the voltage.
According to the electrical installation wiki (2013), “the SPD is designed to limit transient overvoltages of atmospheric origin and divert current waves to earth, so as to limit the amplitude of this overvoltage to a value that is not hazardous for the electrical installation and electric switchgear and control gear.”
Without a surge protector, anything higher than 120 V can create component issues, such as permanent damage, reduced lifespan of internal devices, burned wires and other damages.
Fig 1. Principle of protection system in parallel (Source: http://www.electrical-installation.org)
There are three types of SPD (The Surge Protection Device [SPD] 2013):
Type 1 SPD
The Type 1 SPD is recommended in the specific case of service-sector and industrial buildings that are protected by a lightning protection system or a meshed cage. It protects electrical installations against direct lightning strikes and can discharge the back-current from lightning spreading from the earth conductor to a network of conductors. The Type 1 SPD is characterized by a 10/350 µs current wave.
Type 2 SPD
The Type 2 SPD is the main protection system for all low-voltage electrical installations. Installed in each electrical switchboard, it prevents the spread of overvoltages in the electrical installations and protects the loads. Type 2 SPD is characterized by an 8/20 µs current wave.
Type 3 SPD
These SPDs have a low discharge capacity. They must be installed as a supplement to Type 2 SPDs and in the vicinity of sensitive loads. The Type 3 SPD is characterized by a combination of voltage waves (1.2/50 μs) and current waves (8/20 μs).
The SPD not only protects the equipment against overvoltage, but also the people who will use the equipment affected by the transient overvoltage and those installations. The two main causes of this phenomenon are lightning and electrical switching.
The problems that can be caused by overvoltage vary, and the consequences can be classified in different levels. In addition to equipment damage, which can compromise software and data stored on computers, some other damages may compromise the insulation system of the wires and cause electrical shock to the users of the building.
How Risks are Reduced:
The Surge Protection Device (SPD) is designed to protect electrical devices from voltage spikes while blocking voltage over a safe threshold. When a threshold is over the safe voltage (usually 120V), a surge protector shorts to ground voltage or blocks the voltage to a value that is not hazardous for the electrical installation. While protecting the electrical installation, this device also protects the person who will use the installation
Effects on Productivity:
A surge protection device increases the worker’s protection in a really fast and easy way. It can be portable and attached to the equipment that will be used by the worker. It increases productivity because it prevents damage to the equipment used in construction and avoids delays while work is being performed.
The SPD is specially designed to protect sensitive electronic equipment from surges. There are some important specifications (definitions are provided by Wikipedia):
- Clamping voltage: Specifies what spike in voltage will cause the protective components inside a surge protector to divert unwanted energy from the protected line. A lower clamping voltage indicates better protection, but can sometimes result in a shorter life expectancy for the overall protective system.
- Joules rating: Defines how much energy a surge protector can absorb in a single event, without failure. A lower number may indicate longer life expectancy if the device can divert more energy elsewhere and thus absorb less energy.
- Response time: Surge protectors don't operate instantaneously; a slight delay exists. The longer the response time, the longer the connected equipment will be exposed to the surge. However, surges don't happen instantly either. Surges usually take around a few microseconds to reach their peak voltage, and a surge protector with a nanosecond response time would kick in fast enough to suppress the most damaging portion of the spike.
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