Anyone dealing with mobile or stationary power supply quickly encounters a whole range of terms: power generator, generating set, emergency power generator, standby power system (SPS) or safety power supply system. In everyday language, these terms are often confused or used synonymously. Technically and normatively, however, there are clear differences – and precisely these are crucial when it comes to planning, operational safety and legal requirements.
This article first explains the terms in an understandable way for laypersons and then classifies them technically correctly.
Simple Explanation
Power Generator / Generating Set / Generator
These terms are usually used synonymously in common parlance. They generally refer to a device that generates electrical energy independently of the public power grid. Technically, it consists of:
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an engine (petrol, diesel, gas)
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a generator (the actual electrical machine)
Typical applications:
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construction sites
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agriculture
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forestry
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events
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private applications
Whether one speaks of a power generator, power generating set, generator or generating set makes little difference in everyday life – it almost always refers to a mobile or stationary unit for power generation.
Emergency Power Generator / Emergency Generating Set
An emergency power generator (also emergency generating set) is a power generator that is specifically designed for use in the event of a power outage. The difference from a "normal" power generator lies less in the device itself, but in the application concept:
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power supply when the grid fails
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often permanently installed or prepared
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supplies defined consumers (e.g. heating, cooling, lighting)
A petrol emergency power generator is often used in private or mobile areas, such as for single-family homes or smaller businesses. A diesel emergency power generator, on the other hand, is typical for higher power outputs, longer operating times and professional applications.
Fire Brigade Generator
A fire brigade generator is not a separate technical type, but a specially equipped power generator intended for use by fire brigades, THW (German Federal Agency for Technical Relief) or civil protection. Typical features:
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robust design
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easy operation
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high reliability
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often petrol or diesel generators
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often on a carrying frame or integrated into a vehicle
Technically, this is also a power generator, but designed for special operating conditions.
Technical Classification for Professional Users
Power Generator / Generating Set – The Umbrella Term
Technically, the power generator is the umbrella term for all devices that generate electrical energy. These include:
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petrol generators
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diesel generators
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gas generators
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inverter power generators
A diesel generator is preferably used when:
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long operating times are required
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high power outputs are needed
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continuous operation or high reliability is the focus
A gas generator uses natural gas or LPG and is often used where gas is available or emissions need to be reduced.
Inverter – Special Design of the Power Generator
An inverter power generator is a special design. Here, the generated electrical energy is electronically processed, so that:
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a very clean sine wave voltage
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stable frequency
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quiet operation at partial load
is produced. Inverters are particularly suitable for:
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sensitive electronics
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IT
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controls
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mobile applications with variable loads
An inverter is therefore not a specific application purpose, but a technical design of a power generator.
Emergency Power Generator vs. Standby Power System (SPS)
Here lies one of the most important differences.
Emergency Power Generator
An emergency power generator supplies consumers in case of a power outage, usually:
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manually started
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manually switched on
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without automatic transfer
Typical requirements:
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secure disconnection from the public grid
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supply of selected circuits
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no back-feeding into the grid
Standby Power System (SPS)
A standby power system (SPS) is the technically and normatively defined form of emergency power supply. It replaces the public grid fully or partially and fulfills additional requirements:
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automatic start in case of grid failure
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automatic transfer (grid/SPS)
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monitoring of voltage and frequency
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defined transfer times
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clear integration into the electrical system
An SPS is therefore more than just a generator – it is a complete system consisting of:
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generator
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control system
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transfer switch
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protection and monitoring devices
Standby Generator
The term standby generator is often used synonymously with standby power system. Technically correctly, it describes a generator that:
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supplies power when the grid is completely replaced
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is integrated into a defined standby power concept
In common usage, emergency power generator, standby generator and emergency generating set overlap, even if the technical requirements may differ.
Safety Power Supply System
The safety power supply system is the highest level. It is subject to special requirements and standards, e.g. for:
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hospitals
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assembly halls
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tunnels
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safety-relevant buildings
Features:
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very short transfer times
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redundancy
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regular inspections
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high availability
Not every emergency power generator is automatically a safety power supply system. Clear regulations apply here, including those from VDE, VDI, VDN and BSI.
Summary of Terms
| Term | Meaning |
|---|---|
| Power Generator / Generating Set / Generator | Umbrella terms for power generating devices |
| Emergency Power Generator / Emergency Generating Set | Power generator for power outages |
| Diesel Emergency Power Generator / Diesel Generator | Powerful, long-lasting, professional |
| Petrol Emergency Power Generator | Mobile, flexible, smaller capacities |
| Gas Generator | Uses gas, lower emissions |
| Inverter | Design with electronic voltage conditioning |
| Fire Brigade Generator | Specially designed for emergency services |
| Standby Generating Set | Generator for grid replacement |
| Standby Power System (SPS) | Automatic, standard-compliant standby power system |
| Safety Power Supply System | Critical, norm-bound supply |
Conclusion
Many terms related to power generators are used synonymously in everyday language. Technically and legally, however, there are clear differences – especially between a simple generating set, an emergency power generator and a standby power system (SPS). The decisive factors are always:
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purpose of use
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power requirement
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degree of automation
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legal and normative requirements
Knowing these differences helps avoid wrong decisions in selection, installation and operation.
We at SEV will be happy to advise you on which generating set, generator or standby power solution suits your application – practical, standard-compliant and tailored to your requirements.