What comes to mind when you think of the word "Stabilized?"
Surely, the solidity of a bridge or stability can be compared to the constancy of a relationship, or even the stability of a ship sailing between waves.
The concept of "stabilized" is exclusively linked to the generator's ability to maintain stable values.
The most common questions that make our customers our customers:
Can I connect a Personal Computer to the generator set?
Can I power my audio system with a generator set?
How can I feed a latest-generation Astronomical Observatory?
If you're reading this article, you probably don't have an oscilloscope. You have to give a party on the beach and you're interested in knowing if you can connect your 20,000 euro system to the 299.00 Euro generator set that your cousin will lend you.
We deliberately leave out technical aspects of how important the waveform and other important factors are, as addressing them will not answer your question. We would rather focus on the practical sense of the matter.
Before we talk about stability, it is necessary to make a premise about the load that we are going to feed. Load means the user, i.e. the one we connect to the generator set.
Each load has its own distinctive characteristics, which should be analyzed before each application. In this article, we are not talking about power factor, waveform, load-step, etc., simply because they are topics that deserve to be dealt with separately. However, we keep in mind that the greater the load variations, the greater our stability problems will be.
Do stabilized generator sets exist?
The answer is No. There is no official classification to distinguish between a stabilized and unstabilized generator set. There are performance classes, but not a distinction between stable and unstable. However, this term is commonly used to identify generator set groups that maintain stable nominal values and others that do not succeed in this.
Inverter? Yes, but not always
The most stable sets par excellence are the generators with Inverter technology. A generator set with inverter technology has a thermal motor that is not directly coupled to an alternator.
On inverter generator sets, there are some clarifications to be made:
An inverter generator set is not necessarily suitable for powering electronic equipment. Manufacturers often do not provide clear information about the waveform and its quality. So, be careful before setting up your photo set and powering your valuable equipment with an inverter generator without first verifying its suitability.
Inverter generator sets are commonly used for power ratings up to 6kW.
This last point, linked to the low power that a generator with inverter technology can provide, puts a limit to the scope of application and leads us to reconsider solutions that allow us to have stable, defined generator sets.
One might wonder, "Stable compared to what?" Stable with respect to the parameters set by the manufacturer, and above all, with respect to the characteristics of the users that we will feed, usually linked to the region of the world in which we find ourselves. (Voltages and frequencies are not the same worldwide.)
Voltage and Frequency.
A voltage is considered stable when it is 230V on a single-phase system and 400V in three-phase. We can consider a frequency stable when stopped at 50Hz. (With regard to the region of the world in which we find ourselves.)
The generator set may have at least two elements to stabilize the voltage and frequency values.
- The AVR
- The electronic speed controller.
AVR is the automatic voltage regulator. This is an electronic device mounted on the alternator whose main purpose is to manage the excitation and automatically adjust voltage and frequency according to the load. The voltage regulator is very important because it has a more precise response than old electromechanical systems and prevents problems, such as commuting.
The electronic speed controller is an electronic device mounted on the thermal motor, which regulates the motor speed according to the load. This device decisively influences the voltage and frequency value of the generator set, since the frequency is linked to the speed of the motor revolutions (1500 rpm = 50Hz).
Now you're wondering, but if a generator set has a rotation speed set at 1500 rpm, what sense does it make to have a speed regulator?
In this case, too, we do not want to go too far into the technical aspects of the subject we will be dealing with in the future. Rather, we prefer to respond with something as simple as possible.
The speed of rotation for the motor of a generator is set at 50Hz is 1500rpm, and this speed must be kept constant even when the generator goes under load, since the alternator exerts a torque resistant to the engine shaft according to the active power. Consequently, the speed regulator must act on the fuel flow rate to keep the speed constant.
The difference in stability that a motor equipped with an electronic regulator can give compared to a motor equipped with a mechanical rpm regulator is the response to load variations. The electronic speed controller provides a quick and precise response that cannot be compared to that of a mechanical regulator, and a quick response corresponds to smaller frequency and voltage variation.
Electronic adjustment of the engine revolutions.
For convenience, we can distinguish the two types of regulation in this way:
The mechanical rpm regulator tends to satisfy the load demand requested by the user. It may suffer, it loses its speed and then resumes regardless of the values that change suddenly.
The electronic speed regulator gives priority to the values that the generator set must respect, following them independently of the load that varies, because it loses the load, but does not deviate from the reference values that are considered stable.
Would you like to know what risks we run if we feed a sensitive load with a generator set without AVR and electronic speed regulator?
But above all, would you like to understand, in detail, how to correctly size a generator unit, taking into account the regulation class according to ISO standard?
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