I thought they would be ideal except for the 60 second cool down time
which may be a problem.
The cool down is much less than 1 minute for the size you'd use - more
like five/ten seconds. If it is the reversing condition that requires
a quick cool down, two could be used one for each direction - soft
start is desirable and if not thermistors could also be incorporated
in the triac control - but that would take more understanding and
effort.
I had this robot - small lab Cartesian robot on a large table. All
the gizmos on the table would reset the computer when switched on - we
solved the problem by installing one commercial "brick wall" filter on
the supply to the ancillary machines - just a super filter using many
stages of differential and common mode LC filters.
One of the homoginizers would still occasionally do a reset when it
switched - on the far end of the table with long leads passing by some
of the robot's feedback leads. It would happen once in 200 times and
wasn't considered severe enough to bother with. Watchdog timer would
fix things and we'd only lose an hour of time when it happened - late
at night when no one was around.
The homoginizer also had another fluke that was more vexing - the
still liquid in the vessel would fly out when the motor started -
ramping it up fixed the problem. I went to a radio supply place in
town and bought ten inrush thermistors - six in series made the motor
start slower and fixed the liquid splash problem and also fixed the
rare computer reset problem.
The particular TRIAC based speed controller always switches some time
after zero crossing which would prevent this solution.
It would be a less than ideal solution and might not fix your problem
- but one never knows. Do one?
The motor is about two feet away, it always seems to crash at start up
or reversing while the motor is spinning which seems to indicate a
current related magnetic surge.
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It is foolish, as a rule, with most motors except steppers and some
synchronous motors to reverse direction on a motor that is already
turning. That appears as a short to the supply - and draws heavy
current for a time. In automation applications one almost always lets
the motor coast to a stop before reversing (or electronic braking is
used to quickly stop it) - big motors complain by popping fuses if you
reverse them without a stop first.
Slow Syn made a synchronous motor that turned 600 rpm at 60 cycles -
that particular motor could reverse direction all day long without
hurting it - but it needed a variable frequency drive to change the
speed or a variable sheave pulley type speed adjuster.
I've just realized about 2:00 am this morning that there's a mains
side inductor that is axial/ solenoid in construction and is aimed at
the micro board, I'll replace it with a toroidal and see how it affects
things.
I tried a motor side filter based on these same inductors which made
things worse.
You need an LC network to cut noise - a single inductor is not usually
the answer especially with motor brushes and phase controllers
Most of the crap (EMI/RFI) that hits processors is common mode - so a
common mode choke with some low inductance capacitors on both sides to
ground and across the line are called for.
Long leads to the motor are an antenna that can radiate EMI - the
filter should be as close to the motor as possible - and another as
close to the controller as possible if the leads are long between
motor and controller - triacs tend to be noisy (AM radio near it will
tell you if it radiates)
Don't ignore snubbers. Snubbers are just a cap and resistor that go
across switches (motor brushes) to snub the spikes. As close to the
source of noise as possible - killing noise at the source is 10 X more
effective than trying to eliminate it at the computer.
Snubbers:
When the level of voltage changes suddenly (like a brush leaving one
motor commutator segment and picking up the next on DC motors) the
capacitor absorbs the spike (which is usually very fast - MHZ range).
A resistor is used in series with the cap, to lower the Q of the
circuit so you don't inadvertently make a tuned circuit with some
inherent inductance in the wiring. Resistor & cap is placed across
the noise source close to the source. Point one microfarad, and 100
ohms is a good place to start. Voltage rating of the non-polar cap
should be two or three times the supply voltage (potted AC rated caps
are most desirable)
You may also need a snubber across the relay or switch that switches
current to the speed controller and/or reversing switch and motor.
Snubbers are cheap and often worth their weight in gold.
Don't overlook a power supply glitch too. Some supplies allow the
spikes through to the processor - scope out the digital supply when
the motor is changing direction.