Power Generator Product Facts: A Comprehensive Guide
If you’re seeking a comprehensive guide to understand everything about Gensets (generator sets), you’ve come to the right place. This summary will provide you with insights into what Gensets are, how they function, their usage, and how to maximise the benefits of these versatile power generators.
What is a Generator Set (Genset)?
A generator set, or Genset for short, is a single piece of equipment that combines an internal combustion engine and an electrical generator (alternator). It operates as an electromechanical machine that converts thermal energy from combustion (introduced by diesel fuel) into an AC electrical current through a double-cascade conversion process: from thermal energy to mechanical energy via reciprocating motion (engine rotation) and from mechanical energy to electric energy through the rotation of the alternator.
Generator operating modes
1- Island mode operation
In this mode, the Genset serves as the sole source of energy for the user system. It is suitable for locations without a public distribution network or when users prefer to generate their own energy and utilise the heat emitted by the generator. Examples include self-powered equipment and construction sites.
2 – Generator Operation During a Power Cut to the Distribution Network:
User systems are powered by the distribution network. However, Gensets with automatic activation after a power cut are employed to mitigate problems, material damage, and financial losses caused by blackouts. Examples of applications include data processing centers, hospitals, and industrial facilities operating around the clock.
The Genset is electrically connected to an Automatic Transfer Switch (ATS) panel that automatically switches between available power sources (Genset or network) based on the logic controller settings. Some control panels allow for a short parallel cycle with the network upon its restoration to prevent recurring blackouts.
3-Parallel mode operation
In parallel mode, multiple Gensets operate together to supply energy in island mode. This mode is chosen for two primary reasons:
To ensure service continuity in case of Genset failure or maintenance and to meet high power demands that exceed the capacity of a single unit. Additionally, if there is a significant difference between average and peak loads, multiple smaller Gensets can operate alternately to handle load peaks. It is also possible to use Gensets in parallel mode as emergency backup without operating in parallel with the network.
Parallel Mode with the Network (Long-term or Temporary): Gensets can operate in parallel mode with the distribution network, allowing compensation for absorption peaks not supported by the network or enabling energy exchanges with the network distributor in self-powered applications.
Generator Performance Classes:
Genset performance classes are defined by ISO8528. Alongside basic machine and manufacturer data, each Genset must have a rating plate displaying electrical and mechanical quantities, as well as reference ambient parameters, to comply with this standard.
Basic Electrical Quantities of Power Generators:
Current and Voltage: Electric current is measured in Amperes (A) and represents the flow of electric charge through a wire’s cross-section per unit time. It can be direct or alternating, with Gensets typically producing alternating current.
Electric voltage is measured in Volts (V) and signifies the difference in electric potential between two points. Voltage is generated by charge separation and acts as the driving force for current flow.
Electric power is measured in Watts (W) and represents the work done on an electric load by an electric field per unit time. It can be calculated by multiplying current and voltage (P = I * V).
Production system
Electricity can be generated by either a three-phase system or a single-phase system. The single-phase system is simpler and distributes alternating current using two conductors: a neutral conductor with zero potential and an active phase conductor with variable potential over time.
A three-phase system refers to a three-circuit alternating current with the same frequency and three equal, alternating voltages offset by 120°.
The frequency
Frequency is measured in Hertz (Hz) and is a fundamental quantity of alternating currents. The global standards for power system frequency are 50 or 60 Hz. Some countries operate at different frequencies based on their regions. The electric frequency generated by a Genset is directly proportional to the engine’s RPM and the number of poles on the alternator.
Electrical power
The electrical power rating of a Genset is an essential consideration. It represents the net power available at the power outlet terminal board, excluding the power consumed by auxiliary systems necessary for the Genset’s operation, such as cooling fans.
There are two types of electrical power:
- Apparent Power: Measured in Volt-Amperes (VA), it is the theoretical power that can be absorbed by the generator terminals. The actual work output depends on the load’s efficiency.
- Active Power: Measured in Watts (W), it is the power that is converted into useful work. The load determines how much of the apparent power can be converted into active power. The ratio between active power and apparent power is known as the power factor (cosφ), and the formula that relates them is P = S * cosφ.
To declare the active power of a Genset when the load is unknown, ISO8528 specifies that the nameplate rating refers to a power factor of 0.8. However, the power factor of a load can vary, even within different phases of its operation.
Power ratings
The reference power ratings determine the applicable use for a generator set. These ratings must be specified on the Genset’s nameplate and are governed by ISO8528-1.
COP: Continuous Operation Power
The maximum power a Genset can supply continuously with a constant load, in ambient conditions specified by the manufacturer, and following maintenance intervals.
PRP: Prime Power
The power a Genset can supply continuously over an unlimited number of hours with a variable load, considering the manufacturer’s ambient conditions and maintenance intervals. The average power delivered over 24 hours must not exceed a specific percentage (X%) of the PRP power listed on the nameplate. The engine manufacturer determines the value of X.
The engine manufacturer allows a permissible overload of Y% at regular intervals, with specific values of Y and time intervals set by them. Usually, X is maintained at 75%, while Y is initially set at 10%, but both X and Y can be lower if necessary.
LTP: Limited-Time Power
The maximum power a DEUTZ Genset can supply for a limited operating period of 500 hours per year in intermittent mode or 300 hours per year in continuous mode, following the manufacturer’s ambient conditions and maintenance intervals.
DCP: Data Centre Power
A power rating established specifically for Gensets used in data centers. It defines the maximum power that can be supplied continuously or with a variable load for an unlimited number of hours per year. Genset manufacturers are responsible for ensuring compliance with the engine manufacturer’s standards for the intended application, including site quality, liquid quality, and suitable auxiliary accessories.
Note: The power rating should be specified before purchasing a Genset, as it also affects the selection of the engine.
Ambient conditions of reference
All the performance parameters mentioned above must be specified with reference to the ambient conditions. ISO8528 provides guidance on this matter, with typical reference values including a temperature of 25°C, altitude of 100 meters above mean sea level (m.a.m.s.l.), relative humidity of 30%, and atmospheric pressure of 100 kPa.
The Genset’s documentation should outline the range of ambient conditions within which the machine can operate without performance degradation. Deviating from the indicated conditions may result in reduced performance. Manufacturers determine the performance downgrade based on the affected components, and this downgrade can be determined analytically or through empirical testing in specific cases.
Remember to consult the product documentation, specific product data sheets, and manufacturer’s recommendations for detailed information about a particular Genset model.