Why Generator Speed Is Unstable - Starlight Generator
by Starlight Generator dieselgeneratortech1. Idle speed is not
stable
It
refers to the diesel generator running at idle speed, but the regularity is not
strong, and there are jitter, and diesel generator in the rapid deceleration,
shift or easy to stall with load, this phenomenon is caused by the governor
failure. The main causes of occurrence are the following.
A. Fly ball wear
At
idle speed, the opening degree of flying ball is the smallest, and the spring
slider overreaches the flying ball because of the wear of the small roller of
the ball, which results in an irregular direct collision with the fly ball
body, resulting in instability of idle speed. At this point, touch the joystick
with your hand, will have a slight feeling of being hit.
B. Elastic variation or
improper adjustment of idle spring
When
the diesel generator is in operation, the increase of load will reduce the
speed. If the idle spring or start spring is softened, the feed rod can not
move to the direction of increasing oil quickly to increase the speed, which
will cause the diesel generator to stall automatically when serious.
C. Improper adjustment
of steady speed spring
In
idle operation, because of the small centrifugal force flying ball, speed
control force is also small. If the diesel generator decelerates suddenly, the adjusting
movement of the fuel supply rod may exceed the idle position, causing the
diesel generator to stall. In order to prevent this kind of situation, the
stable spring which is pushing the fuel supply tooth rod to idle position
behind the governor cover; if the spring is too soft or the adjustment is
biased, it will weaken or do not play a stabilizing role, making the idle speed
running unstable.
D. Low pressure oil
supply is poor or contains water and air
This
will result in large and small fuel supply, especially in low speed regions,
which will lead to unstable operation of diesel generators.
E.
Excessive wear of camshaft cone bearing supported by fuel injection pump
In
this case, the camshaft will cause irregular movement in the axial direction,
which makes the speed of diesel generator unstable.
F.
Fuel injection pump supply is uneven, fuel supply is incorrect or injection is
bad.
In
the case of low-speed operation, if the oil supply is not uniform or the oil
supply is not correct, the stability of the rotating speed can be greatly
affected, but the instability of the oil supply is regular and the periodicity
is shorter.
G. Cylinder compression
is insufficient
When
the compression force of the cylinder decreases, the decreasing degree of each
cylinder is not necessarily the same. Even if the fuel supply of the fuel
injection pump is balanced, the combustion situation may still be different,
resulting in the instability of the rotational speed at low speed.
2. runner wagon
The
so-called “travelling vehicle” refers to the slow and slow-time phenomenon of
the diesel generator in the low-speed and medium-speed range, which is the
result of the excessive lag of the speed-regulating reaction to the change of
the actual rotating speed. The reasons for this are the following.
A.
Internal lever of governor is loosened due to wear and tear of connecting pin
hole
In
this case, the increase and decrease of fuel supply in the two-way speed
control motion produced too much direction lag. When the engine is working, the
speed regulation response must lag behind the actual speed change, but the lag
should not be too large, otherwise it will produce a larger regulating
amplitude. The regulating amplitude is too large, that is, when the rotational
speed has increased or decreased due to the increase or decrease of the fuel
supply, the fuel will continue to increase or decrease until the speed exceeds
the adjusting range of the governor. Its strong feedback signal only realizes
the reaction of reverse regulation through the governor, which results in the
speed regulating reaction exceeding the predetermined range, which results in the
phenomenon of "traveling vehicle" that the speed of speed rises and
goes up and down regularly in the vicinity of a certain value.
B. Oil feed rod is not
flexible enough
The
fuel supply rod of fuel injection pump must be absolutely flexible to ensure
the sensitivity of speed regulation reaction. Using a sensitive spring scale to
test the pulling resistance of the tooth rod, the pulling resistance of the
corresponding II,IV,VI,VIII cylinder injection pump should not be greater than
60,90130150g respectively. As a result of rust, deformation of plunger coupling
after fastening, grinding injury of gear ring and tooth rod after plunger
spring break, serious wear of shaft sleeve at the end of tooth rod, and
incorrect fastening angle of fork adjusting mechanism of oil quantity. The bad
installation or fit of the thrust tilting disk and the flying ball seat of the
governor of the domestic fuel injection pump will affect the flexibility of the
fuel feeding rod. When the resistance that affects the flexibility has not
reached the degree that the oil supply tooth rod can not be moved completely,
the phenomenon of "traveling car" will appear (if the oil supply
tooth rod is completely unable to move, the failure phenomenon will be
different depending on the stay position of the tooth rod; For example, diesel
generator can not start, can not stall, speed is not controlled, flying car,
etc.)
C. Improper adjustment
of steady speed spring
This
is similar to the improper adjustment of the steady speed spring when the
idling speed is unstable. The reason for this situation is that the steady
speed spring and the oil feed rod can not work flexibly together.
Jiangsu Starlight Electricity Equipment Co.,Ltd is diesel generator manufacturer/factory in China. Can provide multiple brands of generator, such as Cummins, Perkins, Volvo, Deutz, Ricardo, MTU, Yuchai, Shangchai, Weichai and Wuxi, etc. Contact us: sales@dieselgeneratortech.com
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Created on Mar 31st 2019 21:53. Viewed 276 times.