Nerv
Cast Iron
- Joined
- Jun 16, 2016
- Location
- Alberta, Canada
I have another thread in the DMG forum section about my giant Deckel Maho MC800H restoration ("Contest for the more insane member") but I need some feedback in regards to leakage current and ESR ratings on capacitors and how it may affect the circuit performance if they are outside a certain range of the originals.
I've spent a solid week dismantling and recording the values, types and sizes of every single capacitor on the entire machine. Every... Single... One.
Philips (now Vishay - BC Components) offers these little caps that are all over the Indramat products:
These are Philips 036 Low leakage caps. Almost no capacitor that is stocked with any North American distributors has leakage as low as these units do (.006CV+3µA after 1 min, .001CV+3µA after 5 min). The Nichicon UKL units are very low (.002CV after 1 or 2 min depending on case size), have better ripple current ratings and better life ratings but I'm not an EE and I want to replace all the capacitors with units that are a close a possible to hopefully prevent complications. When I have looked into what others say on capacitor upgrading I keep hearing that increasing the voltage rating is no problem but I'm finding you get an instant increase of your leakage current unless the original wasn't a particularly low leakage unit to begin with and the new ones have less leakage factor. Also I fear if the voltage rating is too much higher than the operating voltage the forming of the cap will not stay as "complete" and may have a negative impact on long term performance. I would love to have all the circuits drawn out and learn how to calculate everything I need but I just don't have time to go to such extents. I have around 144 caps to replace.
This question is for the pros that rebuild drives on at least a semi-regular basis: The Nichicon UKL caps I mentioned before have really low impedance as compared to the originals. If a cap has really low impedance I don't know if this can cause higher inrush current that could damage the circuit, or what values could possibly negatively impact any circuits that are tuned somehow? How critical is low leakage in computer processing type circuits like the controlling side of the drives? I assume leakage will directly affect what voltage the cap will stay at in operation? Does it matter all that much with Electrolytics having such wide tolerances that change with age and temp? I know ESR can go up with age and cause damage but I'm not sure how low I can go without causing problems as well.
I'm going to replace the DC bus caps with the largest capacitance I can fit in the same spot with caps that have higher ripple ratings (sometimes much higher) and lower ESR. I don't know if I go too low on the ESR if it could cause a resonant voltage problem or something in an inverter DC BUS application?
I saw a photo of a Indramat board that appeared to have Nippon Chemi-con caps in the place of the 036 Philips units, but I can't make out what series they are. In my experience Fanucs are quite reliable and they use Chemi-con caps so I like to use them when I can.
Any thoughts on this would be quite appreciated! This is a ton of work but when finished I want all the electrical to be problem free for a couple decades if possible.
I am particularly impressed with the Nippon Chemicon (United Chemi-con) KZN specifications. The seemed to be filled with magic and still have a wide range and great stock locally. The ripple current capability and life expectancy is a whole order of magnitude better than most others I've been going through.
I've spent a solid week dismantling and recording the values, types and sizes of every single capacitor on the entire machine. Every... Single... One.
Philips (now Vishay - BC Components) offers these little caps that are all over the Indramat products:
These are Philips 036 Low leakage caps. Almost no capacitor that is stocked with any North American distributors has leakage as low as these units do (.006CV+3µA after 1 min, .001CV+3µA after 5 min). The Nichicon UKL units are very low (.002CV after 1 or 2 min depending on case size), have better ripple current ratings and better life ratings but I'm not an EE and I want to replace all the capacitors with units that are a close a possible to hopefully prevent complications. When I have looked into what others say on capacitor upgrading I keep hearing that increasing the voltage rating is no problem but I'm finding you get an instant increase of your leakage current unless the original wasn't a particularly low leakage unit to begin with and the new ones have less leakage factor. Also I fear if the voltage rating is too much higher than the operating voltage the forming of the cap will not stay as "complete" and may have a negative impact on long term performance. I would love to have all the circuits drawn out and learn how to calculate everything I need but I just don't have time to go to such extents. I have around 144 caps to replace.
This question is for the pros that rebuild drives on at least a semi-regular basis: The Nichicon UKL caps I mentioned before have really low impedance as compared to the originals. If a cap has really low impedance I don't know if this can cause higher inrush current that could damage the circuit, or what values could possibly negatively impact any circuits that are tuned somehow? How critical is low leakage in computer processing type circuits like the controlling side of the drives? I assume leakage will directly affect what voltage the cap will stay at in operation? Does it matter all that much with Electrolytics having such wide tolerances that change with age and temp? I know ESR can go up with age and cause damage but I'm not sure how low I can go without causing problems as well.
I'm going to replace the DC bus caps with the largest capacitance I can fit in the same spot with caps that have higher ripple ratings (sometimes much higher) and lower ESR. I don't know if I go too low on the ESR if it could cause a resonant voltage problem or something in an inverter DC BUS application?
I saw a photo of a Indramat board that appeared to have Nippon Chemi-con caps in the place of the 036 Philips units, but I can't make out what series they are. In my experience Fanucs are quite reliable and they use Chemi-con caps so I like to use them when I can.
Any thoughts on this would be quite appreciated! This is a ton of work but when finished I want all the electrical to be problem free for a couple decades if possible.
I am particularly impressed with the Nippon Chemicon (United Chemi-con) KZN specifications. The seemed to be filled with magic and still have a wide range and great stock locally. The ripple current capability and life expectancy is a whole order of magnitude better than most others I've been going through.