FR-SE spindle drive problem

[kudos]

Hi

Our FR-SE spindle drive seems to have produced a problem in terms of when u command a speed it takes quite some time to ramp to that speed, when it gets there its not quite fully at speed, and it will not go above 3500rpm (max is 6000rpm)

drive does not go into regen when going from say 1000rpm to 0, regen LED comes on for a split second then drops off and drive just coasts to a halt.

if you go from 2000+ to zero same problem but after while drive will alarm out with over speed this is only error drive will come up with apart from this no errors, no LEDs on or off that shouldn't be etc.

i suspect its a regen/braking fault some where. just thought i would see if any one here could shed some light and give any hints what to check and fault find on.
as repare quotes we have had are not cheap for something that is now 24years old
i dont mind pulling cards and getting meter out to fault finding on it and see if its something a quick easy fix would resolve (new resistor etc)

robert

[cncdiag]

If you command M3 S2000 then M3 S0 do you still get the alarm?
If not your belts are slipping.

[kudos]

hi,
same problem, if u go from high to low in S values or low to high u get huge ramp in effect, and motor jumps in speed ranges it looks/sounds like

like i said regen is not switching on to do any braking
if i command M19 to orientate it has truble doing that also and it will not hold very easy to turn it out of it where is always used to put up a good fight.

rob

[onthebumper]

It sounds like a drive problem. Just to be sure you may want to check your motor leads both at the drive and motor junction box. If one of the leads are not making connection this problem may occur. This drive works under a closed loop system so if you command 6000 rpm's and the drive doesn't see 6000 rpm's from the feedback it should alarm out.

[kudos]

drive will not get upto 6000rpm when commanded gets stuck around 3500/4000rpm
only alarms out when slowing down from like i say high RPM 1/2k to a stop alarms out after about 10s of run down (as does not brake to a stop just free runs)

i play to go through all the truble shooting steps in manual tomorow see what i can find from there.

thx for replys sofare

[Leelund]

Single Phasing or PLG problems.

[Al_The_Man]

or PLG problems.

Yes if it is the type with the P.cct card above the sensor with 4 pots, it may need realigning, if so you need a double beam scope to do it.
Al.

[kudos]

Hi all

thanks for the help and pointers. i spent abit of time on the drive today
i found the phaseB of the PLG (encoder) is not outputting correct. checked at drive end and also inside motor and i get same problem.

does any know where you pick these up from or who makes them
as mitsubishi will not sell direct to us only from an agent that will doulbe or more the price on it.

see atached photos.
thanks.

[Al_The_Man]

I have never found any other source for them, if it has the card mounted above the sensor, have you tried re-aligning it?
Al.

[kudos]

hi al

what i found was phase A and phaseB where right on top of each other not 90deg apart as expected per manual , one set pots does gain, while others offset it from zero
the are pretty on song on voltage and offset wise just the put of phase got me ths is why i belie its not working as it should but i would of expected to not see phaseb at all?

it was quite dirty so i may putit back in set it to right gap etc and see what i get. phases where quite clean on scope.
all other things on drive check out ok. so im sure its in the PLG area of things.

thanks for your help
rob

[kudos]

spent a bit of time on it today, put sensor back in, cleaned it up, and its now working perfect signals are there phA,phB and right voltage and offset,

but spindle is still very slugish. on ramp up to a speed.

did abit more testing
if i comand the spindle from say S2000 to S1500 it will regen and brake very sharp as it should do down to speed.
command from S2000 below S1000 it brakes to ~S1300 then just free runs down the rest (as thoe it will not brake below the base speed)

command from any S to higher value has a very large ramp up curve.


i checked the PLG into drive that is fine, all phases there and correct,
even the converter is changing them into digital form ok on CH pins

checked transistors using the quick resistance check
as found here
FR-SE spindle drive trouble

also did check for waveforms as in manual they are all fine on regen and gen side.

when i scoped the CH11, CH13, CH14 phase check points i am only seeing a ~5v PWM signal not 15v as shown
my next plan is to run through all voltages from PSU but i hope this is not gone again i rember the cost from last time

[Leelund]

Still acts as a phase problem does. Drive sounds like it is good. Regen resistors ohm check out ok? Value should be in electrical manuals. Have you checked motor power leads for continuity? Unwire at the motor and megger check each phase to ground? I think the accel/decel time constant are set by dip switches on this model. they haven't been disturbed? Not sure at this point, just supplying you with more rocks to throw at it. Good luck, sounds like something screwy.