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 You can optimize the performance of
your size reduction equipment by automating the feed
mechanism. Controlling the feed rate to grinders,
crushers and shredders ...
- Helps prevent jamming,
- Improves the uniformity or
structure of ground product, and
- Enhances the efficiency of
subsequent processing operations.
For a precise indication of the load on
the crusher, simply install a current transducer on the
motor lead. The output can be used for reliable
closed-loop control between the crusher and the feeding
mechanism. A drop in load will signal the conveyor or
loader to increase the feed rate. A rise in load will
initiate a decrease in the feed rate.
NK Technologies' current transducers
are available in both self-powered and loop-powered
versions. The split-core design makes installation a
snap.
 A common belief is that auxiliary
contacts attached to a motor starter will indicate when
a load comes on. However, auxiliary contacts only signal
the position of a contactor, not the actual load status.
If a downstream disconnect is opened for maintenance or
the contact sticks, there can be serious consequences.
At a large fish farm, failed aerator
pumps resulted in massive stock looses. Because the
auxiliary contacts remained closed when a pump failed,
the alarm was never activated, the back-up pumps were
not switched on, and the fish suffocated. Now NK
Technologies' current switches have been installed to
alarm the operator and automatically switch on the
back-up aerator pumps.
 Wastewater Pumps can become jammed
with organic matter and cause damage to both the motor
and pump before thermal overloads are tripped.
Alternately, a blockage in the pump suction line can
cause the pump to run dry, overheat and break a seal.
By installing a motor monitor on one
leg of the motor leads you can monitor overloads (jammed
pump) or under-loads (loss of suction).
NK Technologies' smart current
sensors automatically self-calibrate on initial startup.
Built-in user-programmable timers compensate for
short-duration abnormalities and motor startup in-rush.
 Personnel protection is frequently
accomplished by interlocking two or more motors. The
objective is to start the second motor only when the
first is running and driving its load.
By installing a current switch on the
motors you can eliminate complex relay logic, proximity
switches and control panel configuration.
NK Technologies current switches are
frequently used as safety interlocks, in a variety of
commercial and industrial facilities.
- At a grain mill, an exhaust fan
must be turned on before the silo is filled with
flour. Flour dust is very flammable and a static
electric spark can cause an explosion. Current
switches are installed on all exhaust fans.
- A milling operation uses current
switches to ensure that the sawdust exhaust system
is operating as soon as any of the saws, planers or
other woodworking machines are turned on.
- At a commercial laundry the
exhaust booster fan must be turned on when the
dryers are running. Current switches are used to
interlock these operations.
- An aggregate producer has ensured
that both the infeed and outfeed conveyors are
running before starting the crusher by installing
current switches on the motors.
 Good engineering practice dictates
that every output must have a corresponding status
input. On fans and pumps, a current switch can be
snapped over one motor power leg and the output wired to
your automation system.
NK Technologies' self-powered switch
will close when the load comes on, and open when the
load is off. By adjusting the setpoint, you can also
determine whether or not the pump coupling or fan belt
is intact. This reliable, solid-state solution
eliminates the need for temperamental pressure switches,
and reduces the cost of labor and conduit.
The universal solid-state output of
NK Technologies' current switches is compatible with
most automation systems.
Critical loads require a backup pump
that starts automatically in the case of a failure.
Installing a current switch on the power lead of each
pump gives you real-time on/off status. The solid state
outputs can be wired into a PLC or tied into relay logic
circuits to automate the back-up routines.
NK Technologies' current switches
provide millisecond response and ensure fast, reliable
response to pump failure.
For more information, click here to see other
applications from our Applications Guide, or more
detailed application from our Tech Tips pages.
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