Watlow Electric Revision 5 - Manual (Page 61)

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car speed started to slowly increase. She slowly backed off the pressure to the gas
pedal, trying to maintain the 30 mph. This is known as reset, as she was resetting
the engine speed to maintain 30 mph with changing load conditions. This is the
RESET FUNCTION.
The little ole lady now was very close to home and had turned off the highway she
was on. A couple of blocks in front of her, she could see the traffic light was green.
As she was watching, the light turned yellow and then went to red. Upon seeing the
light turn yellow, she took her foot off the gas pedal, because she had anticipated
that she was going to stop, as the light was soon to be red. Now, the rate of
approaching the light was too fast and she knew that she would coast into the
intersection, if she did not step on the brake. By gently stepping on the brake, she
could control the rate of approach of the car to the white line. If, upon stepping on
the brake too lightly, she could overshoot the white line and go into the intersection.
Then, by stepping on the brake too hard, she could undershoot, stopping way back
of the white line and then would need to creep up to the white line. By applying the
proper amount of braking, she was able to stop the car at the white line with no over
or undershooting. This is known as the RATE FUNCTION.
With the OUTPUT FILTER of the Anafaze System, a new function had to be added
to the analogy.
Remember the young man from the proportional section that had way too much
gain? It seems that Daddy did find out and started to look for ways to curb the
young man's appetite for rash action without cutting off his foot or waiting until he
was 40 years old. Daddy's car is an 8 cylinder engine with a 4 barrel carburetor
which reacted very fast to the young man's demand. Daddy acquired a 6 cylinder for
his son to drive and decided after a couple of tickets for squealing tires, to replace it
with a 4 cylinder.
The 8 cylinder is equivalent to no filter action, while the 6 cylinder is equivalent to
a low filter number. The 4 cylinder would be a high filter number. A single
cylinder engine would be equivalent to a very high filter number. By having a high
gain due to youth and a low horsepower due to engine size, a fast response would
not allow squealing of the tires. A response may be made, but not fast enough to
hurt anything. Thus, a high filter setting would reduce high reactions to changing
conditions. This is the OUTPUT FILTER FUNCTION.