There are times when sudden storms occur and with them, electricity blackouts. A power outage may occur by transmission towers falling down, lightning or even by overconsumption which is common in tourist towns during the summer holiday period.
Unplugging appliances during heavy rains has already become a tradition for some families. The goal is to prevent appliances from burning-out. Is it really necessary to pull out the plug? To answer this question, let’s first understand what actually happens during these storms.
How blackouts affect the power grid?
When outages happen, abruptly all electrical appliances are switched off. When the power returns, often the network voltage may be above or below the ideal level. If a too high voltage variation occurs, also called voltage surges, this may cause serious equipment damage. The most devices susceptible to power surges include: TVs, DVDs, computers and landline phones.
Besides these, it’s necessary to be especially careful with washing machines and microwaves, which are controlled by microprocessors. These controllers can burn-out with voltage variation, bringing losses to users.
Refrigerators, motors and heavier devices are more resistant to high voltages and rarely burn-out due to over-voltage. They can be more easily damaged by under-voltage, that is, a supplied voltage below what they need to function.
This happens whenever a refrigerator is submitted to low voltage (which can also be common after the energy supply has been reestablished) causing the motor to not have enough starting power as well as causing overheating in its wiring until the thermal protector triggers. In the long run, these constant cycles can damage the motor. If the motor is turning-on and running, even with a low voltage, it will continue operating.
How does lightning interfere with the power network?
When it’s raining, lightning can strike the power grid that brings energy to your home. Even if lightning struck far from your home, it can move through the electric and/or telephone wiring, until it finds a grounding point, where it will be discharged into the ground.
Some devices that are plugged into outlets may be in the middle of this path, receiving a high power surge. These voltage values are above those supported by the devices and wiring, in turn being damaged.
A voltage surge generally has very high voltage, with a very short duration, in the micro-second range, but enough to cause damage.
One way to reduce the chances of this happening is to ground the electric wiring, which is already mandatory in Brazil. In this way, power surges can be discharged into the ground.