a) Control of two motors (interlocking) Two motors that are
controlled with separate start and stop pushbuttons must
e able to run in two different ways:
• If motor no. 1 is started, motor no. 2 must not be able to
start
• Is motor no. 2 started, motor no. 1 should not be able to
start.
• Two lamps must show which motor is running. Draw
control cu
ent diagram and connect according to the
diagram. Present the coupling to the lab engineer and test
the coupling.
) Control of two motors with time relay A motor M1 is started
and stopped with pushbuttons. Another engine M2 should start
automatically 10 sec. after engine M1. When motor M1 is stopped,
motor M2 must also stop. Two lamps should indicate that the
motors are running, and a third lamp should illuminate when the
elay is active, ie while it counts the 10 seconds. Draw control
cu
ent diagram and main cu
ent diagram and connect according
to the diagrams. Also draw assembly drawings for the contactors
and relays you have used, with contact numbering. Then number
all the contacts in the main power diagram and control cu
ent
diagram. Present the coupling to the lab engineer and test the
coupling.
c) Level control The water level in a tank shall be controlled as
follows: When a inverter is set to position 1, the filling pump P1
shall be controlled by two level switches so that the pump starts
at a defined low level and stops at a defined high level. When a
inverter is set in position 2 , the filling pump P2 shall be controlled
in the same way as described above, ie by the same two level
switches.3
Department of Computer and Electrical Technology If the pump
that is running stops because the associated motor protection
switches off, the other pump must start automatically when the
lower level switch is activated again. Two lamps must indicate
which pump is running. To simulate the level, use two pressure
switches as level switches where the one indicating the lowest
level must (of course) have a holding contact. Draw a control
cu
ent diagram and connect according to the diagram. Present
the coupling to the lab engineer and test the coupling
d) Two pumps Two pumps P1 and P2 must each have their own
set of start and stop pushbuttons. Due to the load on the mains, it
must not be possible to start both at the same time. A time delay
of 5 sec. will be sufficient. That is, regardless of which motor is
started first, it should not be possible to start the other until after
5 sec. Draw the control cu
ent form and connect according to the
form. Present the coupling to the lab engineer and test the
coupling.
e) Direction turner for three-phase motor You must connect a
three-phase motor so that it can rotate one way or the other. Use
three lights that indicate these three conditions. Use thermal
motor protection to protect the motors. Fuses are connected to
your 230 V power outlet.
• First connect without a time relay and lamps, so that the motor
otates clockwise when you press S1, where you then have to
press S0 before you can turn the direction of rotation by pressing
S2 (and vice versa). .If you press the pushbutton for the opposite
otation while the engine is running the scaling thing happen
• Now use a time relay (delayed on engagement) so that you delay
the impact of rotation the other way when you stop the rotation
one of the roads. It is desired that the motor should slow down the
otation speed in that it cannot connect voltage for rotation the
other way before a certain set time has elapsed, eg 5 sec. This
educes the load on the motor. Connect three lamps so that they
show when 1) the motor is running clockwise, 2) the motor is
unning counterclockwise and 3) while the waiting time to turn
the direction of rotation is active. Draw control cu
ent diagram
and main cu
ent diagram and connect according to the diagrams.
The preview coupling to the lab engineer and test the coupling.