Frequently asked questions
Straight answers on auto reclosers, SF6-free switchgear, commissioning and what things actually cost.
About the equipment
What is an auto recloser and how does it work?
An automatic circuit recloser is a switching device on an overhead distribution line that detects a fault, opens to clear it, then automatically closes again after a short delay.
Most faults on overhead lines are transient: a branch touching a conductor, a bird, a lightning-induced flashover. The fault clears itself once the current is interrupted. A recloser exploits that by trying to restore supply automatically, typically two or three times, before locking out if the fault is permanent.
That turns what would have been a sustained outage requiring a crew and a truck into a few seconds of interruption.
What is the difference between a recloser and a circuit breaker?
A circuit breaker interrupts fault current and stays open until someone closes it. A recloser interrupts fault current and then attempts to close again by itself, following a preset sequence.
Reclosers are also self-contained: they carry their own protection, control and measurement, and are built for pole mounting outdoors. A circuit breaker generally sits inside switchgear in a substation and relies on separate protection relays.
What does SF6-free switchgear mean and why does it matter?
SF6 is a gas used in some switchgear as an insulating and arc-quenching medium. It works well electrically, but it has a global warming potential roughly 23 000 times that of CO2, and its use in new electrical equipment is being restricted in a growing number of markets.
SF6-free switchgear such as the SGF/MVT range uses air insulation instead. That removes the leak monitoring, gas handling and end-of-life recovery obligations, and avoids a retrofit decision later if regulation tightens.
What voltage ranges do you cover?
Our auto reclosers cover 15.5kV, 27kV and 38kV. The SGF/MVT switchgear is rated 17.5kV. Voltage transformers are available for 11kV, 22kV and 33kV networks, and lightning arresters from 11kV through to 33kV.
In practice that covers most South African medium-voltage distribution networks.
How long does a recloser last?
The reclosers we supply are rated for 30 000 mechanical CO cycles and 30 000 operating cycles at rated current, and are specified for operation from −40°C to +55°C at up to 100% condensing humidity.
Practical service life depends far more on installation quality, earthing, and whether anyone inspects the unit and its backup battery between operations. A battery nobody has checked is the most common single point of failure we see.
Buying and pricing
How much does a recloser or switchgear cost in South Africa?
There is no useful list price, and any supplier who gives you one without asking questions is guessing.
Cost depends on the voltage class, the current and fault ratings, the control and communications specification, and whether installation, commissioning and voltage transformers are included. A 15.5kV recloser for a rural feeder and a 38kV unit with full communications and remote control are very different quotes.
Tell us the network voltage, what the equipment has to do and whether you need installation, and we will give you a firm figure rather than a range.
Do you supply outside Gauteng?
Yes. We are based in Midrand and supply across South Africa. Installation, commissioning and maintenance work outside Gauteng is quoted per project, including travel and any site-specific requirements.
Do you supply spares and provide ongoing support?
Yes. Technical support and spares are part of what we do rather than an afterthought once a system is commissioned.
That covers routine inspection, fault finding and diagnostics, firmware and configuration updates, and emergency breakdown support.
Installation and commissioning
What is secondary injection testing?
Secondary injection testing injects test currents and voltages directly at the protection relay, rather than through the primary circuit, to confirm the relay picks up, times and trips exactly as its settings intend.
It verifies the protection logic and the settings without needing to energise the primary equipment or create a real fault, which is why it is a standard part of commissioning a recloser.
What is protection coordination and why does it matter?
Protection coordination means the protective device closest to a fault operates first, so the smallest possible section of network is disconnected.
Get it wrong and a fault on a small spur trips the main incomer instead, taking out an entire feeder and every customer on it rather than a handful.
This is why network integration verification is a separate commissioning step from functional testing. A recloser can pass every test on its own and still be badly coordinated with the protection upstream of it.
How long does commissioning take?
It depends on the scope, the site and whether an outage window is available. A single recloser on an accessible pole is a different job from a multi-panel switchgear lineup that has to be coordinated with existing substation protection.
We scope commissioning as part of the quote, so you get a realistic figure rather than a surprise on site.
Do you service equipment you did not supply?
Yes. We maintain and support Magvatech equipment, and we can look at recloser and switchgear installations from other manufacturers as well.
If you have equipment that is misoperating, out of support, or that has not been inspected in years, tell us what is installed and we will tell you honestly whether we are the right people to help.
Still need an answer?
Tell us about your network and what you are trying to solve, and we will come back with a straight answer.