printer friendly version

Protecting your electrical equipment

Lightning season is yet again upon us (almost), and we have yet to have a season free from Eskom’s rolling blackouts – planned and unplanned – by whatever polite name they choose to refer to them. And while we know that lightning is a clear danger to electronics, so is load shedding.

Load shedding is not just about working without power; every time the power comes back there is a short voltage spike that damages your electronic equipment. Over time, this equipment will fail and it is a matter of chance whether your manufacturers or insurance companies will honour claims for surge damage due to the ever increasing number of claims they are facing.

To get a handle on surges, lightning and the power issues electronic security equipment is facing, Hi-Tech Security Solutions asked Roelof van Jaarsveldt of PSS Distribution and Bruno Jones from BFR Digital for some insights and advice.

Hi-Tech Security Solutions: What are the real dangers of surges when it comes to load shedding? Will better quality products be able to withstand the surge when the lights come back on or are all electronics at risk?

Van Jaarsveldt: When the power is restored after the given period of load shedding, the increased voltage that was sent down the power lines will create a surge for the first few properties in line with the transformer on the street. For optimal surge protection, one needs to look at online UPSes. The alternative to this would be connecting surge plugs to your equipment as all electronics are at risk as this affects anything connected to the power.

Jones: Rotational load shedding is wicked! It damages electronic devices, appliances and industrial electrical equipment, and worse is that your conventional surge protection does not protect your sensitive electronics from electrical power surges caused by rotational load shedding.

This kind of sucks; you have paid good money for surge protectors and now I’m telling you that the stuff does not protect your devices from load shedding. Worse yet is that you are probably experiencing this currently at your office or home. Normally, the first thing to fail from a load shedding voltage surge is your mission-critical security system.

We also know that rotational load shedding in South Africa is here to stay. Most energy experts say that it will be with South Africans until 2026 – a minimum of 5 years.

Most people believe that their insurance cover will replace devices damaged by Eskom’s power outages, however, although most insurance cover provides clients with peace of mind against damage from lightning strikes, this is not the case for load shedding damages. So, read your policy.

There is also an impression that buying better quality equipment helps withstand the surges caused by rotational load shedding. Most equipment manufacturers use off-the-shelf switch-mode power supplies in their products. The quality of these power supplies is what will determine how the product will cope with load shedding.

Hi-Tech Security Solutions: How can one protect your electronic equipment from these surges – apart from unplugging?

Van Jaarsveldt: Surge plugs have become popular over the past few years; they are also compulsory for some insurance companies to honour a claim for surge-damaged goods. The ultimate solution for protecting against surges would be an online UPS; they offer the highest possible level of protection. If these are all in place, ensure that they are working.

Jones: Unplugging your electronic equipment before the scheduled load shedding and plugging it back in 10 minutes after the power comes back on is the best form of protection. However, it is not foolproof. When a suburb is turned off or turned on, it causes ripples throughout the entire supply grid. The further you are from the suburb being load-shed, the lower the level of the surges your electronics will experience.

It would help if you had surge protection. But what type of surge protection?

Standard mains surge arrestors make use of MOVs (metal oxide varistors). These MOVs are connected from line to earth, that is from live to earth and from neutral to earth. If you happen to have a more expensive mains surge arrester, then there will probably be a MOV between live and neutral.

The MOVs have a typical clamping voltage of about 275 Volts. While the voltage of the circuit remains below the metal oxide varistor’s clamping voltage, it remains non-conductive (dormant). But when the clamping voltage is reached, the metal oxide varistor starts to conduct. In this state, the MOV connects the live or neutral to the electrical earth to dispose of the electrical surge energy safely.

The problem with load shedding is that most surges from load shedding remain below the metal oxide varistor’s typical clamping voltage. Because of this, your electronics, appliances and industrial electrical equipment get fried by electrical surges before your surge arrestor even starts working.

What is needed is a device that tracks the mains sine wave and provides a small window of operation that has a low transient let-through voltage. This device comprises an electronic circuit that is more than a single component.

Hi-Tech Security Solutions: What about lightning protection? Protecting against a surge is very different from protecting against lighting, so can these two jobs be done for a reasonable cost with a single device or solution?

Van Jaarsveldt: A complete lightning protection system consists of external lightning protection, which refers to a lightning rod outside your house, and internal lightning protection, which is surge protection. Surge protection as well as a UPS have been recommended by numerous suppliers as they offer a buffer on the strike, giving the equipment a chance to withstand the excess voltage coming in due to the lightning strike. Protecting the entire distribution board is also an option that is becoming increasingly popular. This can be achieved by installing surge arrestors.

Jones: For lightning, we need to add our trusted MOVs. Remember that MOVs are designed to protect against transients from lightning (high-voltage spikes and surges). Therefore, to have a surge arrestor that works for both lightning and load shedding, both sine-wave tracking surge arrestors and MOVs need to be combined into a single surge arrestor.

This hybrid-type surge arrestor is larger than a MOV-based surge arrestor, but it is a load shedding surge arrestor and a lightning surge arrestor in one.

Hi-Tech Security Solutions:What advice would you give to a residential estate if they wanted to ensure all estate electronics are protected from surges and lighting?

Van Jaarsveldt: In a situation where more than one point would need protection or when the equipment is not all within proximity, we recommend a surge arrestor to be installed in the distribution board. A surge arrestor is a device that protects your equipment on an electrical circuit against transient voltages.

Jones: I would recommend our hybrid-type 60 kA surge arrestor at the BD on the circuit supplying power to their electronics and our hybrid-type 20 kA surge arrestor at the actual equipment being protected.

Hi-Tech Security Solutions: Can one monitor your electronics in some way to determine if there has been surge damage before the devices stop working?

Van Jaarsveldt: Once a device is damaged due to a surge, the common failure would be the power supplying components. Your electronics will generally have a fuse to protect against excessive voltages; once this is blown, it will reflect as one of the indications that a surge has passed through the equipment.

Jones: Unfortunately not. Our surge arrestors could be damaged by multiple smaller surges or one massive surge. I believe that monitoring the number of surges and the state of the surge arrestor is a wasteful expense. Let’s say you have been monitoring how many surges your arrestor has ‘arrested’. From the spec sheet, you believe that your surge arrestor is halfway through its useful lifespan, but then you experience a close proximity lightning strike. That’s it, your surge arrestor is cooked!

Hi-Tech Security Solutions: What solutions do you offer for surge and lighting protection?

Van Jaarsveldt: At PSS Distributors we offer the latest technology in power protection equipment. The range of surge protection devices include constant voltage transformers, UPSes, traditional surge plugs, and in certain situations, automatic voltage stabilisers. We can protect incoming power, satellite connections, network lines, telephone lines, CCTV signals and more.

Jones: We offer an extensive range of hybrid-type mains power surge arresters and surge arresters for communications cables. Our most popular low-voltage surge arrestor is for PoE (Power over Ethernet) devices like CCTV cameras.

To properly protect PoE devices in the field is expensive. The surge arrestor is the cheap bit, it is the electrical earthing infrastructure needed that is expensive. This is why we introduced Surge Blockers. Our PoE Surge Blockers require no electrical earthing connection and are extremely effective when a few simple installation guidelines are followed.

Share this article:

Further reading: