Surge protection is a feature across both general household power strips and rack-mounted power distribution units. A power strip that is equipped with a power surge protector is protected against sudden voltage changes in the electrical circuit. 

Not all surge protectors are created equal - some have more capacity to protect against bigger voltage spikes while others have faster response time. So how does a power surge protector work and how do you know if it’s working as expected?

How a Power Surge Protector Works

A power surge protector works by detecting a sudden change in voltage and diverts the excess voltage to ground so it does not reach devices. Some surge protector models absorb the excess voltage and dissipate the energy as heat.

In Australia, General Purpose Outlets (GPOs) found in homes and offices provide 10-15 amps and 230-250 volts. Industrial and commercial facilities operate at a higher power level of 10-50 amps and 415 volts to provide a more stable power supply to heavy duty equipment. 

A power surge occurs when the voltage goes above these normal levels. Higher than normal voltage in the electrical circuit can damage devices beyond repair - causing melted wires and increasing the risk of electrical fires. A surge protector serves as a first line of defence against power surges for connected devices in a circuit.

Power Surge Protectors in Power Strips

Surge protectors in power strips and PDUs include transient-voltage-suppression (TVS) diodes and metal-oxide varistors (MOVs).

TVS Diodes

A TVS diode diverts excess voltage by shorting the circuit. When a specified voltage threshold is reached, the two ends of the TVS diode come close enough to form a ‘spark gap’ that shorts the circuit. When the surge has passed, the TVS diode resets itself and allows current to flow normally.

TVS diodes are at the lower end of surge capability (up to 15,000 A). However, it has the fastest response time compared to MOVs and gas discharge tube surge protectors. TVS diodes are used in appliances that are prone to voltage spikes, such as consumer electronics.

Metal-Oxide Varistors

An MOV is a type of resistor that restricts current flow based on voltage. At normal voltage levels, the MOV has a high resistance, causing the current to flow normally through to devices. 

When voltage reaches past a certain threshold, the MOV's resistance decreases, allowing it to conduct the excess current and divert the extra voltage away from devices. 

MOVs have a high surge capability of up to 70,000 A, making them suitable for use in both residential and industrial power strips and appliances.

Do All Power Strips Come With Surge Protection?

Not necessarily. In Australia, power strips only have surge protection if the product description has a joule rating and an RCM (Regulatory Compliance Mark). Be careful when buying power strips from overseas - some countries do not have regulations for electrical equipment so the power strip may not actually have surge protection as advertised. 

According to Wiring Rules AS/NZS 3000 the maximum surge protection required for domestic use is 40,000A. The recommended surge protection for industrial and commercial equipment is 100,000A.

How to Tell If Surge Protection Is Working in a Power Strip

High quality power strips with surge protection usually have an LED bulb displaying the operational status of the surge protector. In most models, a green LED light labelled “surge protection” indicates whether the surge protector is active. When the LED light is unlit or displaying red instead of green, it may indicate that the surge protection is not working or that there has been electrical damage. 

This is only a general rule - each power strip or PDU will come with its own instructions for assessing surge protection status. 

RackLink stocks a range of power strips and PDUs for industrial and commercial applications - our PDUs are equipped with effective surge protection and circuit breaker features suitable for high-power setups within a rack-mounted environment. We can manufacture custom power PDUs for both horizontal and vertical mounting arrangements, with up to 45 outlets in GPO and IEC outlet configurations.   

 

Get in touch with our team to find out how we can create the ideal surge-protected PDU for your needs.