Emergency Generator
A diesel generator, also known as a Genset, is a piece of equipment that consists of a diesel engine and an electric generator/alternator. These two items work together to convert diesel fuel into electrical energy.
Diesel burns at a much higher temperature compared to other fuel sources making it more efficient and powerful. The engine converts the fuel into mechanical energy. This energy powers the alternator by spinning the alternator rotor which converts the mechanical energy into electrical energy. A diesel standby generator can run for hours, days, and even weeks with the proper maintenance and fuel supply.
Generators come in a variety of sizes and strengths depending on their purpose. The two main types of generators are portable vs. standby generators. Portable generators can be delivered on a truck in a time of need. Standby generators are a permanent fixture of a facility and require regular maintenance.
What equipment can start an emergency generator?
- ATS Switch
- SCADA or BMS
- Protective Relay
- Manual Start
Wet Stacking
Wet stacking is a condition that occurs when unused diesel fuel, accumulated moisture, and carbon particles are allowed to gather in the generator exhaust system. This can happen for a number of reasons but is typically caused by diesel fuel not being properly burned off during use. As a result, a dark muddy liquid congeals in the generator’s exhaust stacks — hence the term wet stacking.
Wet stacking is hazardous to genset injectors, exhaust valves, and other functional features. And, when left untreated, wet stacking can inhibit the performance of your generator as well as significantly reduce the lifespan of your unit.
What causes wet stacking?
- Letting a generator sit unused for long periods of time.
- Allowing a generator to run under its designed operating temperature.
- Allowing a generator to run at less than 60% of its rated output.
- Running a generator with an incorrect air-to-fuel ratio.
- Having too little fuel in the generator.
Automatic Transfer Switch
In emergency power systems, transfer switches are used to provide a continuous source of power for lighting and other critical loads (automatically or manually) by transferring from the normal source of power to an emergency source of power in the event that the normal source voltage falls below preset limits. Utility Power is routed through the automatic transfer switch and into the switchgear.
Typical ATS Components
- Normal Power Source
- Emergency Power Source
- Transfer Mechanism
- Load Terminals
- Neutral Connection
- Logic Panel
- Instruments
- Space Heater
ATS Maintenance
- Visual Inspection
- Contact Resistance (Normal/Emergency/Bypass)
- Insulation Resistance, with care not to damage solid state components.
- Simulate loss of normal power.
- Return to normal power.
- Simulate loss of emergency power.
- Simulate all forms of single-phase conditions.
- Verify normal source voltage-sensing and frequency-sensing relays.
- Verify engine start sequence and time delay upon transfer.
- Verify alternate source voltage-sensing and frequency-sensing relays.
- Interlocks and limit switch function.
- Time delay and re transfer upon normal power restoration.
- Engine cool down and shutdown feature.
