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Thanks for the feedback!

Hi guys, I have been investigating the characteristics of an DC electrovalve. I have these data: Vsupply: 80Vdc r1: coil resistance (510 Ohms) r_shunt: (to measure current) (118.1 Ohms) I apply a step of 80V to the Rshunt+coil and get this graph. Time constant is about 108ms. So tau=L/R...

After reviewing my calculation I was wrong about radiation (I used ºC instead of ºK for the formulae!) So for a disc of similar dimensions at 210ºC I get: h(convection)=4,5 W/m2K h(radiation)=10 W/m2K With my very simplistic assumptions seems that radiation is as important as convection at...

Thanks zekeman for your detailed reply, I have not R1 but still get a 90%fit to their model, I interpret C1 as the outer part of the disk in contact with the pad, and C2 as the inner part or zone not in contact with pad where the heat flux goes after the initial "heat up". I have calculated...

Thanks guys, your detail is far more that expected! Really I `ve a simulation of the brake discs manufacturer; after tuning it, my model reproduces almost the same results for Tª (over capacitor C1) with same acceleration/decceleration profile used in their simulation. I understand that in...

Hi, I`ve developed a "lumped capacities" thermal model of a brake disc. ----------|--R1-|--------------- ^ | | | (I) ---C1 ----C2 -R2 | --- ---- - | | | | -------------------------------- The input is...

Ok, I think that more o less understand it, I found this:(http://tinyurl.com/382a25m) Digitizing RS-170 video: A typical digital image produced by video digitization would have a resolution of 512 (horizontal) X 480 (vertical) pixel resolution and would have individual pixels with a 5:6 aspect...

Thank you IRStuff, I was cofused indeed. So if I have my camera with PAL output and nice BW, have I 704 × 576? I suppose that the CCD+processig electronics of the camera should be able to get first that number of pixels and then have some nice electronics to generate a good BW PAL signal...

Hi, I have a client that wants a CCTV recording system with 4CIF resolution for an on board aplication. I have seen that CIF is thought for digitizing PAL field frames(352 × 288) (1 field giving 288 lines and each horizontal line sampled to 352 pixels) 4CIF (704 × 576) seems that might be...

Hi, Jraef,I think don´t understand what has to do "DC injection braking" with "regenerative braking appearing inmediatly" and what relation has to damaging semiconductors. Maybe you mean some transient interaction between remaining magnetic flux and DC injection....? It is not a jerk...

Hi, I have a traction application with a VFD-Motor supplier. It gives me information about response times to change from 100% powering to 100%regenerative braking. (about 4s with jerk limiting 0.8m/s^3) What it puzzles me is that before passing to braking it waits for 1s dead time without...

First thanks for your replies. I really appreciate I words what I mean is that lower atm pressure means that you need less cylinder "high side" pressure to get the same effort, but this "less" represents only in my case 0.2bar from about 10bar (working pr.), so is really not representative. On...

So I assume that I am not saying nonsenses by supposing that have a reduction of 20% flow rate. Now my second derivative is: Ok I have 20% less flow rate BUT for getting a constant effort (Freq) in my cylinder I really get Freq=5N A=1^-5m2 Return_spring=-4N (1bar = 10^5Pa = k) At sea...

"If the rated discharge is 10.3 barg then instead of 11.36 bara you'll be getting 11.16 bara (98%). So the capacity of the compressor is only decreased by 2% (q2=q1*P1/P2). If the discharge pressure is lower then the impact is greater (at 5.2 barg, it is 3.5%)." Sorry but I don´t see it...

Hi, I have a project in Mexico city, >2000m above sea level, 80% of standard atm pressure. My pneumatics supplier says that there is no matter for consumption calculation or compressor nominal rate (X normal liters/min) relating the altitude, altought we are really very near the limit. Thay...

Thanks for the reply but the units don´t match, and think that you didn´t take account that Pmin Pmax were relative pressure (manometric): [volume]/[Pressure]-[Volume]*[Pressure]/[Pressure] Anyway reviewing it I realised that my formula was wrong: The correct I think it is: Considering...

Hi, I am reviewing a pneumatic calculation. One step is to calculate how many liters of air (at normal conditions) are needed to fill up some pneumatic springs. The calculation does the following for getting the volume to add needed (Vn) to get a predefined pressure, (liters at normal...

Thanks guys! very valuable information, there are a lot of confusion out there about this subject.

Thanks for your reply. It is really an impressive application. I have seen very interesting information about the subject in thread237-149826 thread237-220699 Frome there I read that seems to exists drives that are capable of sensorless full torque at zero speed, but normally an encoder is...

Hi, After some months reading about vector control I have been looking for information about how is the real performace of the main variables of the motor (currents, field synchronous speed) when it is commanded torque at zero speed (i.e. as holding brake). I would like having an insight in...