Finding an effective power solution for blackouts and load-shedding
In South Africa, the flicker of a light bulb or the sound of a buzzing electrical appliance has become a cause for celebration. The realisation of power returning brings on a sigh of relief. Africa’s second largest economy has threatened to regress as rolling blackouts keep the country in the dark. The blackouts are scheduled and limited, affecting different areas at different times, in a process meant to convey stability, even as the national grid struggles. These organised power cuts are known as ‘load shedding’ (blackouts).
Load-shedding, or load reduction, is undertaken countrywide as a controlled option to respond to unplanned events to protect the electricity power system from a total blackout. A country-wide blackout has serious consequences, which can occur when there is too much demand and too little supply, bringing the power system into an imbalance – shutting the power system in its entirety.
With the increase in load-shedding, we are reminded about the inconvenience of no power. Whether planned or an accidental ‘blackout’, the power returns with a power-back surge causing damage or even destroying electrical appliances. During planned load shedding, cable thieves may steal copper cables resulting in loss of neutral. This results in equipment receiving 3-phase (+400 V) and not the 220-230 V, again damaging electrical appliances.
5 main power problems:
The following problems can negatively impact the solar inverter if the right protection isn’t correctly installed to prevent the below events from occurring whilst in function:
- High voltage – As power fluctuates due to unreliable mains or poor distribution network, the mains voltage can either drop or rise. A sustained over voltage event can be catastrophic and cause instant irreparable damage. (Consider installing a SVS, voltage stabiliser, where utility is supplying high/over voltage for long durations. This will facilitate faster charging of the batter pack).
- Low voltage – Similarly, low voltage can occur often during fluctuations, over stretched distribution network, excessive demand to the size of the utility or being at the end of a long distribution line. Low voltage is particularly damaging to equipment. (Consider installing a SVS, voltage stabiliser, where utility is supplying low/brown out voltage for long durations. This will facilitate faster charging of the battery pack).
- Power back surges – Commonly occur after power cuts. As the mains supply resumes, it usually returns with a surge which could be quite high and damaging in some instances. Ensuring the power has settled before resumption is important.
- Spikes and surges – Power spikes are short pulses of energy on a power line and contain high voltage. These spikes only last a few milliseconds, but they have the potential to cause great damage to sensitive equipment. Often equipment does not fail right away; however, in many instances when it does, this seriously affects the shelf life of any electrical equipment.
- Loss of neutral – When the instance of LoN occurs, the line voltage will rise from a normal 220/230 to 400/415 V causing instant catastrophic damage and even risk of fire. The AVS30 inverter accepts the input power source from the ac mains, battery, solar modules and switches between various operation modes depending on the operational conditions. This will expose the inverter to high or low voltage, which will damage its circuitry.
The AVS is installed to protect the inverter from unreliable damaging mains power by disconnecting the input main power when it’s outside the limit of acceptable voltages.