There is a deluge of products claiming to protect Electronic equipment against Lightning and Surges (transient overvoltage). 95% of them are sub-standard, misleading and of no effect.

However, when subjected to tests, many of them have an unacceptably high let-through voltage. The wrong let-through voltage is disruptive and harmful to your electronic equipment.

This is what a client should ask before purchasing a surge protector.

What then should one expect from a quality & effective surge (transient overvoltage) protector?

Key requirements Explanation

In order to provide effective protection, a surge (transient overvoltage) protector should:

• Be compatible with the system it is protecting survive
• Have a low let-through voltage, for all combinations of conductors
• Not leave the user unprotected, as a result of failure, and
• Be properly installed.

Compatibility

It is key that the protector does not interfere with or restrict the system’s normal operation.

• It is undesirable for mains power supply protections to disrupt or corrupt the continuity of power supply and for them to introduce high earth leakage currents.
• Protectors for data communication, signal and telephone lines should not impair or restrict the systems data or signal transmission.

Survival

The protector should therefore be rated for a peak discharge current not less than 10kA. Since Lightning discharges sometimes exceed 200kA, surge (transient overvoltages) caused by the secondary effects of Lightning are unlikely to have currents exceeding 10kA.

Let-though voltage

The Larger the surge (transient overvoltage) reaching the Electronic equipment, the greater the risk of interference, physical damage and hence system downtime. Thus, the transient overvoltage let-through protector should be lower than the level at which interference or component degradation may occur.

Modes of Protection

A transient overvoltage can exist between any pair of conductors:

• Phase to neutral, phase to earth and neutral to earth on mains power supplies, and
• Line to line and line to screen/earth on data communication, signal and telephone lines.

Thus, the transient overvoltage protector should have a low let-through for all combinations of conductors.

Protection failure

When in-line protectors (such as those for data communication, signal and telephone lines) fail, they take the line out of commission, thereby preventing damage to the system. However, it is unacceptable for protectors on mains power distribution systems to fail short circuit. If these protectors suddenly fail they will leave the system unprotected. It is therefore important that protection for mains power distribution systems have a properly indicated pre-failure warning, whilst protection is still present.

Installation

The performance of transient overvoltage protectors is heavily dependent upon their correct installation (eg the length and configuration of connecting cables). Thus, the transient overvoltage protector must be supplied with documentation detailing the installation practice. The installer is required to conform with these installation instructions.

At FullSpectrum, we assist organizations safeguard their Critical Electronic infrastructure.

With our industry based and tested expertise in Power quality services, we are able to satisfy our clients by Specifying, Procuring, Supplying, Installing and Commissioning of quality surge protectors.

Contact us today

Victor Oyedu, FNSE, FNIEEE, CPQ.
Power Quality and Energy Management Specialist.
Publisher at Afrienergyonline.com & 
CEO, FullSpectrum Energy Solutions Limited, Nigeria.