Yamaha EF4500iSE - Inverter Generator Theory & Diagnostics Manual Download

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Yamaha Generator Theory & Diagnostics Guide

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.

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.

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.

Characteristics of Electronic Breaker

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