A generator could be overloading due to a failing AVR (automatic voltage regulator) or a battery in poor condition. Either of these can cause voltage drop from the generator resulting in overloading occurring.
It’s also a good idea to ensure that the generator has fresh fuel and oil levels topped up. If these are not maintained it can result in the generator not working optimally leading to situations where it trips with nothing plugged in. This post will discuss why the generator is overloading, especially with nothing plugged in from an electrician’s perspective.
Generator Basics
A generator is a machine that converts the energy in a fuel such as petrol or diesel into electricity. The electricity generated can be either single phase or three phase.
The electricity we use everyday is a very specific voltage and frequency. We can’t have a random voltage coming out of the generator. For the USA this is 120 volts at 60 Hertz. For AUS/UK/NZ this is 230 volts at 50 Hertz. Appliances we use everyday need these specific voltages and frequencies to function properly or problems start to occur.
When this voltage or frequency deviates, weird things start to happen. Firstly, we can cause permanent and expensive damage to electrical equipment such as TVs, fridges, dishwasher’s, and other electronic equipment. Secondly, we can cause unusual problems to occur such as the generator tripping with nothing plugged in.
The generator ensures the correct voltage is output via the AVR or automatic voltage regulator. This requires that the generator battery is in good condition. The generator ensures the correct frequency via the speed of the generator. This is typically kept at a constant speed via a governing system.
Now that we know the basics of generators (relevant to this article) let’s look at what might be causing it to trip on overload.
Overload – What’s that?
A breaker tripping on overload is a protective mechanism to ensure that cables and windings don’t draw more current than they are designed to. This is because overloads generate heat.
This heat burns out cables and windings leading to short circuits, fires and other expensive problems. The overload breaker detects an overload and shuts off power before any damage is done. Here is why an overload could occur.
Generator Overload With Nothing Plugged In? – Reason #1
Faulty AVR
The AVR or automatic voltage regulator ensures that the generator is putting out the correct voltage. If the AVR is faulty resulting in a voltage drop significantly lower than 230 volts or 120 volts it can cause problems. Volt drop causes current to increase proportionally. This increase in current can cause an overload to trip. Checking the output voltage of the generator should give an indication of whether this is the problem.
Generator Overload With Nothing Plugged In? – Reason #2
Poor Battery Condition
The battery also helps ensure that the right output voltage is achieved. If the battery is in poor condition it can result in a lower output voltage tripping a breaker on overload. A battery in poor condition is a common occurrence with standby generators due to its seldom use. Loose or dirty connections on the battery can also give the impression that the battery isn’t good.
Generator Overload With Nothing Plugged In? – Reason #3
Mechanical Problem
As mentioned earlier, an overload will trip to ensure that cables and windings don’t burn out. If the generator has been running on stale fuel or low oil levels it can cause damage to internal components. These mechanical components can run inefficiently resulting in poor power output, unnecessary heat and other problems resulting in the overload tripping.
Stale fuel and bad oil are common problems with standby generators that haven’t been used or serviced in a while.
Generator Overload With Nothing Plugged In? – Reason #4
Double Check Loading
Confirming that there isn’t load on the generator is also important. Often people get generators that are too small and underestimate how much electricity they actually use. This obviously will trip the overload breaker.
Electricians Perspective
Ensuring that the output voltage is correct via a multimeter will give some indication why the generator is overloading with nothing plugged in.
This will help determine if a faulty AVR or battery is the cause. A mechanical issue is much more serious and expensive but can be remedied in the future by ensuring that there is oil and fresh fuel in the generator.
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