Transformer
Transformer is used
to convert ac voltage from one level to a different
level. Only AC voltages can be used. The principle
of conversion by by magnetic flux It can have a
minimum of 4 leads and more to any number, based on
how many outputs are put out. The input leads are
not connected physically to the output. The main
purpose of a transformer is to step up or Step down
the voltage. It is also used to isolate the machine
physically from the input power.
Check: Check the
resistance across one set of terminals, using a
Multimeter. It should have some resistance. It can
neither be short or open. Also none of the terminals
can be shorted to the ground or body of the
transformer. In the case of Star Type the Center of
the transformer is sometime grounded to make the
three phase equal with respect to the ground.
Voltage Regulator:
Voltage regulator
is a circuit which can regulate the output load from
fluctuations. Though there are several designs
available, there is a quick and easy way to regulate
voltage, with a single chip. 7805, 7905, 7812, and
7912 are commonly used regulators. 78 means a
positive voltage and 79 mean a negative voltage. 05
mean 5 volts and 12 means 12 voltage. 7805 - means a
regulator for putting out to plus 5 volts, 7905 -
means a regulator for putting out to minus 5 volts.
Integrated chips
also called as IC:
There are a lot of
chips which can range from 4 pins to 132 or more are
used in different parts of electronics in a machine
tool.
Analog IC: Op-amp
This is a very
important device, which one would see in every DC
axis and spindle drives. This is used, in most
cases, as comparator. It is used to compare the
speed of tacho meter or similar devices from the
velocity feedback side, to the specified command
voltage from the control side. It puts out voltage
based on the two inputs mentioned above, which in
turn will run the motor at a specific speed. Op amp
does the job keeping the speed controlled. IC 741 is
the most popular Ic used in circuits.
Check: It involves
a little work in testing the op amp. It is easier to
change it and verify since it is an inexpensive
component. Every op amp is different, that is why it
is called and analog chip. Care has to be taken to
adjust the output voltage to zero. When the input
terminals are shorted out (Meaning the input between
two input terminals is zero which is also called
command voltage). Every analog drive will have an
adjustment called Balance or Drift. This Pot can be
used to adjust he Output to perfect Zero when the
drive is not moving.
Digital IC
There are 100s of
different IC, which performs from a simple and or
operation to very complex logic like
microprocessors. Major kinds to keep in mind are TTL
Logic and CMOS logic. TTL logic uses 5 volts for
power supplies. CMOS uses mostly 12 volts and should
be careful in handling those since static from our
body can hurt it. It is always a good idea to wear
the ground strap.
Check: Checking an
IC involves some work. There are some IC testers
available in the market, which might be some help.
Author: Ven Swaminathan.
Email - Ven@cnconestop.com
For more information visit
www.cnconestop.com/CNC.htm
