Q. What is the design principle of your PowerShield?

A. The heart of our component circuitry is a metal-oxide varistor: a device which alters its resistance depending on the amount of voltage present. The higher the voltage, the lower the resistance. It is designed so that, while it allows a small ‘leakage’ current to exist at all voltages, this amount is minimal. It acts more like a short as the voltage exceeds the specified clamping voltage and it does this in a linear fashion.

The PowerShield is a diverting unit. Instead of absorbing energy, it diverts it harmlessly away from any connected equipment.

Q. Can you explain the different surge current ratings?

A. Peak surge current rating and maximum surge current capacity are two different readings, and mean two different things. Peak surge current rating is the highest single pulse of current PowerShield is designed to dissipate/divert. The maximum surge current capacity is a cumulative value for all of the phases. For this reason, both three-phase and single-phase systems may have the same peak surge current rating but different maximum surge current capacities.

Q. Does the PowerShield have any effect on ‘drop outs’?

A. ‘Drop outs’ aren't recognized power quality activity. However, PowerShield isn’t designed to supply energy. The device will do nothing while the power is off, but will provide protection as soon as the power is reapplied. This is of particular value if the outage is very short and you haven’t had time to shut down all equipment before the power is reapplied. There is some benefit in what are described as 'micro-outages’, which occur in less than 1/16th of a cycle (.0013 second). These events are uncommon, but they can disrupt electronic equipment.

Q. UPS suppliers claim their systems provide satisfactory surge suppression. Can you comment

A. UPS surge suppression is meaningless unless the UPS has had its surge suppression system rated. Because such systems aren't tested by an independent, internationally recognized testing laboratory, any such claims are unsubstantiated.

Having been developed to meet the stringent testing requirements of Underwriters Laboratories 1449, and the ANSI/IEEE standards for surge arrestors/suppressors, PowerShield has a much higher surge current capacity. This determines how long it can be expected to provide protection.

Typically, failure of the surge circuit in a UPS puts the UPS offline and forces the system to switch to battery power. This is extremely confusing to customers because the building power is still on. Moreover, the surge suppression built into a UPS is intended to protect the UPS itself, rather than the connected equipment.

UPS systems are generally not installed to protect all of the equipment in a building. PowerShield can protect literally every outlet: including your UPS!

Q. Why is PowerShield called a surge suppressor/arrestor?

A. We qualify under both standards for testing by Underwriters Laboratories, a nationally recognised, independent laboratory.

Q. What is the difference between a surge suppressor and a surge arrestor?

A. A surge arrestor is designed to be installed on the service side of your electrical installation and isn't protected by any of the components of your electrical system.

A surge suppressor is designed to be installed on the load side of your electrical system, so your own wiring and breakers protect it. The major benefit of our design is that it is sufficiently resilient to be installed on the service side of your electrical system, yet sufficiently sensitive to serve as an extremely responsive surge suppressor.

Installing equipment on the service side provides the maximum protection possible. In other words, it protects all your equipment from the effects of a catastrophic event within the capabilities of the PowerShield. Installing anywhere on the load side means that anything ‘north’ of that location (in the direction of your utility supply) is at risk.

Q. Why is power quality getting worse in my area?

A. In most cases it’s less likely that the quality of power is deteriorating, and more likely that your equipment is now simply far more susceptible. Think back just 10 years: how many AC motor drives, microprocessor controlled robots, and multi-giga-hertz personal computers were then installed in your business? The more sophisticated, faster and smaller our control equipment gets, the more sensitive it becomes.

Another factor that increases companies’ exposure to power upset is our inclination to network everything together with conductive interface standards.

Q. Why install a PowerShield at the main panel?

A. Directly connecting the suppressor to the bus-bar (or main terminal) greatly reduces impedance in the surge path, which results in significantly lower let-through voltage (the surge remnant that passes through a suppression device and attacks your equipment).

The main panel is your first entry point to your business and it is through this portal that the most immediate and damaging transient events enter – lightning and utility capacitor switching.

PowerShield has been developed to react extremely quickly to protect the connected equipment. Because we can stop the first impulse of an oscillatory transient – and because we do this at an extremely low level – any follow-on oscillations are practically non-existent.

Q. What is the significance of the UL 1449 second edition listing? Why was it changed?

A. Underwriters Laboratories’ original standard was more than 13 years old. Because so much had changed in the industry during that time, the old standard simply no longer reflected businesses and their equipment.

A number of additional tests were added to the standard. For example, equipment must now be capable of withstanding a 25,000-amp fault current at the full-phase service voltage – it even requires the PowerShield to withstand over seven hours of sustained high voltages! In all, the old standard contained approximately 39 pages of requirements – the new standard is a full 102 pages long.

Q. Does PowerShield require maintenance?

A. No. PowerShields are completely solid-state. There are no moving parts, and no parts that require measurement or testing.

Q. What does let-through-voltage mean?

A. This is the amount of volts that the system will allow to pass during an event. This voltage isn't necessarily consistent throughout the duration of the event, but it's the maximum amount recorded. You may notice that one device has a higher let-through voltage than another. This simply means that it coped better with the elevated voltage.

If you have a question about power protection issues that is not answered here, we will be happy to answer it for you. Contact us.