Phase perfect maintenance

[Jeff Bartley]

Darwin helped me too, super good dude, in fact I have only good things to say about everyone there.
David, does your unit have 8 line caps? Or did they tell you to replace the caps in the back of the unit? They only told me to replace the two line caps.
My repair wasn't quite 2k but a hassle none-the-less!

[David Zaret]

yeah my unit has 8 caps, and he definitely said to replace all of them. which model do you have?

[Warren Lake]

how much are the caps. The two rotos I have both same companies 30 years on one and never done, first one likely 50 years old but not used last 10 had a cap fail once, lady replaced it and disconnected one to balance something better too long to remember and sadly that company gone.

is this a common thing that Electronic brakes and CNC stuff is hard on the caps? I have one machine now that has an aftermarket electronic brake Short Stop is the brand. Might even take it off, I dont need one that has a brake when non of the others have a brake other than manual ones on shapers and bandsaws. I like to hear motors wind down and hear the bearings in the final seconds.

[David Zaret]

the caps from PP were $185 for a set of 8. for the cost of that unit, and the cost of potential down-time, that's ... cheap, in my book. yes, motors that have inductive brakes are indeed hard on these caps. i don't fully understand the mechanics of it, but my understanding is that when the brake kicks on, it generates an inductive load against the motor, and that load ultimately hits the caps which "absorb" it and regulate the leg voltage. Darwin from PP said that they have one customer with a bunch of inductive-braking machines, and they replace their caps proactively every 6 months. i have mid-sized machines, the biggest inductive braking motor on the Martin shaper, and i'll probably keep an eye on the caps but plan on replacing them every 12-18 months or so.

[Jeff Bartley]

David,
I have the 10hp or 35amp unit. Are the 8 caps you where told to replace all input line caps?

[David Zaret]

yeah. i have the 110 amp unit, which is effectively two of the ~50 amp units side by side, connected with fiber optics to control the timing. there's four caps in each, and yes, he wants me to replace all of them.

[Rod Sheridan]

I thought it was just a capacitance check with a meter and if within specs you are good to go, you guys are saying that PP says replace them every 2ish years regardless?

mark

Yes, non sinusoidal waveforms are very hard on AC capacitors, as are higher frequencies because the XR of the cap is inversely proportional to frequency, resulting in higher currents.

The manufacturers really do know a lot about their product................Regards, Rod.