Working Principle of Electromagnetic Start Switch
by Starlight Generator dieselgeneratortechThere are two kinds of control
switches in the electric start system of generator set: electromagnetic type
and mechanical type. The electromagnetic switch is driven by the
electromagnetic force to pull the fork to start. When starting the diesel
engine, press the switch. At this time, the circuit is as follows: the battery
switch, the connecting post 5, the iron absorption coil, the connecting post,
the generator and the iron battery. The current flowing through the iron
suction coil makes the core magnetized to produce suction force, and the moving
contact is sucked down and closed with the static contact. At this time, the
circuit flowing through the starting switch is as follows: the battery terminal
4 moves the contact point and the static contact keeps the coil; the attracting
coil is connected with the pole 3 and the starting line of the starter is
equipped with an iron storage battery.
At this point, the current flows
through the DC motor, but because the current is very small, the motor can not
rotate. The direction of current flowing through the coil is the same as that
of holding the coil, and the magnetic flux is the same. Therefore, a strong
magnetic force is synthesized to draw the moving iron core to the left and
drive the fork to engage the starting gear with the flywheel. At the same time,
push the copper sheet to the left compression reset spring.
When the active core is moved to
the left extreme position, the copper sheet connects the circuit between the
terminal 3 and the terminal 4. At this time, a large amount of current flow
into the DC timing line, motor rotation, into the starting state.
After startup, the switch is
released, the current in the coil is cut off, the core pushes the suction
force, the dynamic contact jumps away, and the current between the holding coil
and the suction coil is cut off through the dynamic contact and the static
contact. The circuit in the switch at this time: the storage battery is
connected with 4 pieces of copper bar and the third pole attracts the coil to
hold the coil and tie the iron battery.
Because the current in the coil
is drawn in the opposite direction, the magnetic flux produced by the coil is
opposite, and the magnetic force counteracts each other, resulting in the
suction of the moving iron core, and the active iron core drives the starting
gear back to the original position under the action of the reset spring. Cut the
circuit between Pillar 3 and Pillar 4 and stop the motor.
What should
be paid attention to in the automatic Air switch of the Control Panel of Diesel
Generator set
1. Correctly select rated current
of release
In the case of an automatic air
switch of DZ10-100 type, the main contact allows for a long period of time to
pass through 100A rated current. Which to coose depends on the capacity of the
generator. If the generator used is 30KW and the stator current rating is
54.1A, the release with rated current of 60A should be selected as close as
possible and slightly larger than the rated current of the stator. If the
current is too large as 80A, if the generator is overloaded for a long time and
the heat release does not work, the automatic air switch can't protect the
generator from overload. If 40A is selected, the generator is rated for about 1
hour, and the release takes place, which causes the automatic air switch to
trip and cause the power failure. The rated current of the release should
therefore be specified at the time of purchase.
2. Correct selection of
instantaneous Action rated current
The rated current of
instantaneous action is selected according to the result of short circuit
calculation. The setting value of the current should be set by the switchyard,
and the requirement must be put forward to the manufacturer when ordering,
otherwise, the maximum value should be set when leaving the factory. In
general, the instantaneous operating rated current of the automatic air switch
purchased in the store does not meet the requirements and, if necessary, an
additional short circuit protection device is added.
The main switch of the diesel
generator set control panel can not be closed
The main switch of control panel
of diesel generator set refers to the automatic air switch of primary loop.
What are the reasons for the failure of the main switch and how to deal with
it?
I Manual
operation, main switch can not close
1. Under-voltage release coil has
not voltage, or coil joint contact bad or broken wire, burned. Power should be
plugged in to repair or replace coils.
2. The gap between the armature
and the core of the undervoltage release is to large, so it will not be absorbed
after the power is turned on.
3. The operating mechanism is not
in place, each axis in the mechanism is nor flexible or the top of the lever
has burr. Adjustment of bottom, coaxality between panels, lubricating oil.
Grind the top of the lever, deburr, and lubricate.
4. The underpressure release
lever is adjusted too high, which causes the screw on the half shaft to move
up. The armature of the shunt release is not reset or the push rod on the
release shaft is too high. The occlusal amount of lever and half axis was more
than 1.2 mm.
II Electric
operation, main switch not closed
1. Press
close button, relay does not work
Generally, the button is in poor
contact, the relay coil is broken, the relay auxiliary contact is normally
closed to be normally open or diode, and the capacitor is broken. The repair
method is: repair or replace the button; connect the disconnection or replace
the coil; correct the relay contact wiring Replace damaged diodes and
capacitors.
2. Relay
action, main switch cannot be closed
The bridge rectifier diode is
burned and the electromagnet coil is broken. The diode should be replaced,
connected to the wire break or the coil replaced.
3. Press the
button, the relay is closed, but the main switch can not be closed.
The electromagnet rod stroke is
not enough or the electromagnet rod bolt is loose. Adjust the gap between the
moving iron core and the bracket to ≤0.5mm, and
tighten the bolt.
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Created on Nov 22nd 2018 01:14. Viewed 308 times.