I actually did sort of the same thing, added an SSR so I can
independently power
steppers and spindle. (to preserve the functionality of the
buttons/switches on a
Paxton/Patterson enclosure for a Sherline lathe and mill.)
I didn't read the whole thread but you said "but its not intentionally
connected to those 2 other than as a power src when its enabled"
SSRs have some tricky behavior, I made it work, but it needs some
wiring trickery. My enclosure already had two SSRs, that were wired
together, to switch it
from "manual to CNC mode".
What is the wiring issue, maybe I can help?
Ron
On 2/21/20 12:14 PM, Gene Heskett wrote:
On Friday 21 February 2020 11:53:16 Nicklas Karlsson wrote:
Greetings all;
I have added a 40 amp SSR in the relay box with the two that are
sequencing the spindle's psu startup for a soft start, but its not
intentionally connected to those 2 other than as a power src when
its enabled. Except this one is to be enabled by the E-stop.out
signal when its on, f1 pushed once after start. The idea is to turn
on motor power etc to the remainder of the system with the F1 key.
Be aware that failure mode of SSR I am pretty sure is short ciruit so
that it does not turn off. Expect SSR is implemented with a thyristor
or mayb triac and they will not turn off a load with low power factor.
Even though it is very likely to work most of the time I would not
fully trust a F1 button for emergency stop.
I'm aware of that, but so far I have had zero failures with the hoymk
brand of 40 amp 450 volt SSR's from mpja.com since using 2 of them to
soft-start the spindle motor psu for about 3 or 4 years now. 2 of them
are controlling all motor power including a 1.5 horse vfd from a pi
running the sheldon. So when lcnc isn't running, the Sheldon draws less
that 10 watts, and its monitor draws 11 watts.
I would consider these two above as a problem if you need some safe
way to turn of machine then for example changing tool or climbing into
the machine for some reason or for some reason need to touch a part
that might cut fingers.
Machine is a small grizzly g0704, a 400 lb tabletopper on a stand, and
the only time it would be called upon to interrupt the full load would
be an estop situation. Its worst starting load would be the two
switchers for xy, and the line powered z combined driver unit. The
spindle power only comes on after this is on, and the normal shut down
kills that first by inserting that 200 watt 51 ohm R back into the
circuit a few hundred ms before a total shutdown. And theres a wall
switch between the machine and its computer that kills the computer and
interface if thats needed.
It will see the machines full load amps at E-stop shutdown. So it will
get tested heavily. Its actual switch is in series with a switch/breaker
in a multiplug strip screwed to the box that I have been using to shut
off everything but the computer and interface. All I'm doing is makeing
it shut off its own motor power completely when the job is done. I'll
remap the an m2 into an m2.1 to do that.
While I'd much rather have a big t-bar contactor, have you priced those
lately, not to mention you need boosters to handle the coil currents
they need. These are $11 a copy and a sub 10 mill logic signal from a
bob can control them. Simplicates things nicely.
Thanks Nick.
Cheers, Gene Heskett
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