Yamaha EF4500iSE Theory & Diagnostics Manual page 12

Yamaha Generator Theory & Diagnostics Guide
EF3000iSE new model guide
Instantaneous Frequency Fluctuation &
Instantaneous Voltage Drop
Momentary frequency fluctuation:
■
The frequency and voltage fluctuates momen-
tarily when the load is altered if the engine can-
not keep up with the load changes in the case
of conventional synchronous generators.
In contrast the momentary frequency fluctuation
of Yamaha inverter generators is as stable as
the commercial power source with this new
inverter system.
The frequency fluctuation rate of Yamaha inverter
generators is less than 0 .1% .
Momentary voltage drop:
■
However, the momentary voltage drop occurs,
when large electric load is turned on. This is
caused by the fact that the electric energy
stored in the condenser runs short momentarily
until the engine speed picks up to sufficient
engine speed to compensate the energy short-
age in the condenser. The ratio of such momen-
tary voltage drop and the rated voltage is
defined as momentary voltage drop rate. The
momentary voltage drop rate of Yamaha inverter
generators is usually less than 20%. Naturally,
the smaller the load capacity is applied, the
smaller the momentary voltage drop becomes.
In case of incandescent lamps, large amounts
of current flow the moment it is switched on. The
rush current may be as large as 10 times the
rated current of the lamp. Therefore, when a
large wattage incandescent lamp(s) are switched
on, the momentary voltage drop is greater.
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Electronic Breaker
As opposed to the non-fuse breaker (NFB) used in
synchronous type generators, Yamaha inverter gen-
erators use an electronic breaker circuit housed in
the control unit. When output from the control unit
exceeds a specific limit, output is automatically inter-
rupted to protect the generator from damage.
The control unit is designed to continuously monitor
the output current for overloads, and if the current
overload continues longer than a specified time,
output is interrupted.
Characteristics of Electronic Breaker
When using induction motors or similar devices
(such as underwater pumps) which require a large
starting current with the generator, the current will
not be interrupted even if the starting current
exceeds several times the generator's rated output.
Only when the large over current continues longer
than a specified time, the control unit will interrupt
the circuit, and in this way it resembles a mechani-
cal NFB.
The engine must be stopped and power interrupted
to the control unit in order for the system to reset
after the electronic breaker has activated.
NOTE: If a device's power switch is ON when it is
connected the generator and the generator is sub-
sequently started, the device may unexpectedly
activate or start up as a result, creating a potentially
dangerous situation.
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