7
WI-LSC905/3003-02
ALLMAND LSC Light Sequence Controller
SEQUENCING ON
Generally an engine-driven generator is required to start with a load connected. It is not uncommon for the
load to be applied to the generator all at one time as the engine is coming up to speed. It is also common for a
generator set to have a fixed RPM in order to maintain a required frequency, usually 1800 or 3600 RPM. As a
result of these requirements the engine starting system can have additional loads that can result in premature
failures of the starter motor due to overcranking. In addition the typical diesel engine would include a fuel
solenoid that controls the flow of fuel to the engine electrically. The fuel solenoid typically includes a pull coil
that retracts a mechanism to allow fuel flow when the engine starter is cranked. Excessive engine cranking
and excessive engagement of the pull coil in the fuel solenoid can result in overheating and burnout of the pull
coil.
By having no load, or sequencing the loads on, the engine starter and solenoid will not be affected.
Benefits of Sequencing the Loads ON:
1. Potentially less requirements on the engine starter.
2. Less cranking of the starter and faster starts results in less coil failures in the solenoid.
3. A smaller horsepower rated engine may be adequate due to no load during engine start.
4. A smaller horsepower rated engine may be used as the loads can be sequenced on as some types of
loads have higher starting loads than running loads such as electric motors etc.
5. A smaller generator may be used as the loads can be sequenced on. Some types of loads require a
significant inrush to start such as electric motors, etc.
6. The engine can be started and allowed to warm up before loads are applied.
7. The engine oiling system will be allowed to build up to normal oil pressures before the load is applied.
AUTOMATIC LOAD SEQUENCING OFF
Generally an engine generator set will have the potential to be shut down while under load. This could be the
result of the operator’s failure to disconnect the load prior to shut down or as a result of the automatic
shutdown due to low oil pressure, high water temperature, or running out of fuel. Loads applied to the genera-
tor during engine shutdown can result in failure of the generator regulation system as the regulator attempts to
maintain the generator output while the RPM is decreasing to zero.
By automatically sequencing the loads off before the engine is shut down, the generator regulation system will
not be affected. Sequencing the loads off can occur during manual shutdown or during any automatic shut-
down such as low oil pressure, high water temperature, or low fuel.
Benefits of sequencing the loads OFF.
1. Regulation system is not damaged as no loads are applied during shutdown.
2. Engine can be allowed to cool down with no load before shutdown. This can be especially important in
turbocharged applications to prevent cooking the oil in the turbo.
3. Generator can be allowed to cool down with no load before shutdown.
By combining the automatic load sequencing ON and OFF with an engine auto start control any machine
attended or unattended can be assured of these benefits.
Not
for
Reproduction
