Mike, I am a bit nervous of SSR's and dust collectors because the heavy impeller means a slow start-up and a longish period of very high current. I have seen 5 times rated current for about the first second....
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Mike, I am a bit nervous of SSR's and dust collectors because the heavy impeller means a slow start-up and a longish period of very high current. I have seen 5 times rated current for about the first second....
I use an electronic box which turns the dust collector on when one of my DC connected machines is turned on. I know next to nothing about electronics but the control box mounts near the main breaker box and has a round disk which is inside the breaker box. The black wire for any machine I want to control runs through this disk which senses current and turns the DC on and then turns it off about 10 seconds after the machine is turned off.
I think that this would address Gerald's concerns because the relay would need to only control the router or spindle.
Wayne
Gerald, SSRs can be found with higher current ratings than the SSR-240D25 that I suggested. The SSR-240D25 is a DC controlled SSR handling up to 240AC at 25 amps.
Lynn, I would build something a little more robust than what you describe. I would use a metal box to contain the SSR and SPST and an AC outlet receptacle. Usually, I would run a dedicated line from the breaker panel to the 'box'. The hot conductor of that line would go from the breaker to SPST, from SPST's other terminal to SSR terminal no. 1, from SSR terminal no. 2 to the hot side of outlet receptacle. A neutral conductor from the panel would go directly to the neutral side of the outlet receptacle. A ground conductor would go directly from the common ground in the panel to the outlet receptacle.
Gerald, although that (interference) could very well be, I've been using mine since early '01 with no problems. All my interference problems came before that. My bot would move by itself without interaction from me, the software, or the router. :^0
Mike, I see in the spec sheets that a SSR can handle about 10x rated current for one cycle of the AC, but I can't see what it will handle for the first 60 cycles (1 second). Anyway, if I go that route again, I would probably use a smallish SSR to drive a contactor.
Scott, I probably should have been more careful with the cabling and screening. It doesn't help that out here we have 230V as our lowest voltage.
Now that we have a full-time operator, "Van", there is no longer a need for our ShopBot to "auto-switch" - Van does that. (Our MechMate "auto-switches")
Lynn, are you doing anything for DIY currently? I gotta say I'm a big fan of your handmade music shows... maybe I just like to watch Kentucky Thunder jam... good stuff.
Mike... I've got a dedicated 20 amp circuit in the new shop for the router and dust collector and turnning them both on at once doesn't trip the breaker, so this surge I'm hearing about shouldn't be a concern, should it? Seems like if I'm not tripping a 20 amp breaker, the 25 amp rated SSR should do it. Putting a mechanical switch in the line makes a lot of sense. Any chance of posting a photo of yours, or e-mailing one to me?
I'd just go with the finger on the Z axis like Robert shows, but I want to activate/deactivate the dust collector too.
What is the output voltage on the terminals in the control box (PRT, not Alpha)? Is it 5vdc?
Rob... no, I've not done anything for DIY since we taped the 7 episodes back in 2002. The producer is still doing Handmade Music though. We just got DIY back at the house as part of a digital cable package, and I see they've done a series on violin making, banjos, and I hear even one show on steel drums! I saw one a couple of weeks back on electric guitars. I'm glad you enjoyed the shows. It was a blast doing them.
Everyone here has been a big help today. I appreciate all the input.
Thanks,
Lynn
The reason I mentioned the surge is because our shop's circuit breakers were all okay until the dust collecter arrived. The DC nameplate said 11 Amps and it immediately started tripping a 20 Amp breaker. So I put an Ampmeter on it and saw it starting off at near 60 Amps. We got a "slower" 20 Amp breaker to cure the problem.
Lynn,
Sorry, I don't use the device that I described (my Colombo spindle is already controlled by the Shopbot - factory settings). The circuit is something very similar to circuits that I used to design in process control computers for the photo industry. I would normally install an SSR that is rated 2X the breaker current, not that it's necessary, but having a $30 device fry and stop all production is false economy. Gerald's advice about having the SSR control a contactor is excellent. You'll lose the zero-crossing feature, but a mechanical contactor would handle on-rush surges. However, as you said, you're not tripping a twenty-amp breaker, so the contactor option might be something that you would add if needed. Be sure to use shielded cable on the low voltage control side of the SSR and ground the shield (one end only) to your common chassis ground to avoid electrical noise.
Typically, TTL-style logic (the electrical stuff in the control box) usually 'sinks' current, meaning that one side of the control circuit is connected directly to 5VDC and the other end is connected to the output. When the output is 'off', it is actually at 3 to 5VDC. When the output is 'on' it is low, somewhere between 0 and 0.7VDC (at least that's the range of voltages acceptable to TTL logic, which most controller cards use). The whole object of the control circuit in an SSR is to turn on an internal L.E.D. That L.E.D. expects to see about 10ma of current and a voltage between 3 and 30 VDC. Because of the L.E.D. circuit, there is no direct connection between the control side of the SSR and the high voltage AC side. Opto-isolation is probably the main reason to use an SSR. At any rate, depending on where you buy the components, everything should cost between $50 and $100 and take about 30 minutes to wire up.