What is a Standby Generator?
A standby generator is designed to run during mains power failure. It’s used for emergency backup and is not intended for daily/continuous duty.
- Emergency backup only (intermittent running)
- Typically no overload capability
- Ideal for offices, retail, farms, healthcare and critical standby systems
Standby kVA can look “higher” than prime for the same model, but it must not be treated as a continuous rating.
What is a Prime Generator?
A prime rated generator is built for regular use where the generator is a main power source or runs for long periods with varying loads.
- Suitable for long running hours
- Handles variable loads better than standby duty
- Often allows a limited overload period (manufacturer dependent)
- Common on construction, utilities, events and remote sites
Key Differences at a Glance
| Feature | Standby | Prime |
|---|---|---|
| Purpose | Emergency backup | Main / long-term running |
| Operating hours | Limited (during outages / tests) | Long running hours with variable load |
| Overload capability | No | Often yes (manufacturer dependent) |
| Typical use | Offices, hospitals, farms | Construction, remote sites |
Why Choosing the Correct Rating Matters
Using a standby generator for prime duty can cause overheating, premature wear, poor fuel efficiency, and potential warranty issues. Overspecifying prime when you only need backup can push costs up unnecessarily.
