Siemens Mm420 Drive..........

[kme]

Yes, I know they make good bookends :slap

Did a favour job last week, and swapped out a faulty one, driving an extract fan for a hotel kitchen.

However, they`ve had three times this week, when the fan stops. Drive shows an error code ( maybe F02) - voltage out of spec.

I`ve since spoken to the guy whose job it is - he went out to the old drive with errors - found a melted connector on L2 supply, and remade the terminations.

So I`m wondering.............

If the fan motor is failing / leaking at running temp, and trying to draw more power - could that be the cause?

OR....Given the physical location of the actual motor unit, I don`t believe it gets cleaned regularly - two other 12" ducts would have to be dismantled, 4 floors up (internal to building, in a service riser), before being able to access the fan motor.

It isn`t my bag - I simply copied the settings from the original drive onto the new one - but he`s asking me, as its on the fringes of his knowledge.

My initial suggestion is to go and clamp the phases, and see if one is drawing an imbalance.

My questions are twofold:

1. I`m assuming that I`ll get much more info from the drive, if I were to connect it to the lappy, rather than using the BOP? I understand the s/w is freely available, but the connecting cable is special (but I think a local member on here has one?).

2. At the moment, when the drive errors out, they have to go to the 4th floor service cupboard, and operate the local isolator, to reset the drive. Is there an option to have the drive do a manual reset under fault condition? Can it be done from the BOP, or would it need the s/w?

Thanks all

KME

 

[Sidewinder]

KME,

Just off out.

Xmas do thing with kids.

Will chat tomorrow.

Which FW & model code?

 

[kme]

Right - update (snakey, you`ve heard most of this!)

The new drive has had to be bypassed (again) - the contractor wants us to do a full interrogation, to determine the problem.

So before I buy one, does anyone have a connecting kit (plugs in place of the BOP, provides RS232 port) for a lend?

The drive is erroring on overcurrent  - which would generally be a regen issue on deceleration, overdriving the DC bus.

But the trip is occuring at full speed, with no speed alteration request. The rampdown time is set at 1 minute anyway.

DC bus is at 535V, bus limit is set at 800V

We do NOT have any test results on the fan motor itself; which is the current focus of my suspicions.

Thoughts? Apart from putting in a "decent" drive - they want to keep like-for-like

 

[OnOff]

Try here, there's even a specific FORUM..................sad gits!  :lol:

https://support.automation.siemens.com/WW/llisapi.dll?query=420&func=cslib.cssearch&content=adsearch%2Fadsearch.aspx%3Ftab%3D2〈=en&siteid=csius&objaction=cssearch&searchinprim=_searchinprim_&nodeid=99&x=16&y=8&cssearchengine=NEW&x=0&y=0

 

[Riggy]

Maybe too off the wall, but how about fan IS overspeeding due to external influences? I'm thinking along the lines of wind direction at the discharge point, lifts moving in the building, etc.

 

[OnOff]

Maybe too off the wall, but how about fan IS overspeeding due to external influences? I'm thinking along the lines of wind direction at the discharge point, laftifts moving in the building, etc.

The Siemens forum talks of power supply fluctuations and caps breaking down..............

 

[Sidewinder]

KME,

Overcurrent is NOT d.c. bus overvoltage.

Which is it mate, I'm confused now.

What is the exact error code?

 

[kme]

:slap

Cheers

Paul - its over voltage mate - according to mfrs, 3 possible problems (error is F0003 iirc)

1. DC bus over limit

2. AC supply voltage over high limits

3. Regen issues caused when fan slows down.

The drive was swapped out last saturday.

Sunday - tripped out mid day (no speed alteration)

Mon - ditto

Tues - no trip

Weds - tripped out mid afternoon ( no speed alteration)

Thurs - ditto

Fri - ditto

Sat: Tripped seven times throughout the day. Drive now bypassed (again)

The old drive acted ok until you asked it to start the fan - then it threw out a comms error

Paddler - Thanks, but I`m going to have to get one quicker - need the front panel connector for next weekend.

n.b. The fan is cleaned annually, apparently - they have pics. So I`m leaning toward a motor issue - or a faulty drive.

 

[kme]

Doubtful it's a motor issue for an over voltage dc bus fault, connect the motor up DOL for a couple of days with an overload and see what happens. Mmm Good idea.

The laptop will tell you no more than the BOP for fault finding, what are you expecting the siemens software to diagnose? Was hoping to get deeper into the fault log? And dump the full parameter list from the old drive, to compare them to the new drive. 

Are you 100% sure the acel and decel rates are correct ? 96% mate

They are sometimes set up in 2 place ? Yeeeeeeeeemaybe....

What ramp type have you set ie ramp to stop / coast / dc injection ? As the wrong setting of one of these wont help ! Does the fan rotate backwards in a breeze if stopped ? Ie is the Inverter trying to start a backwards running fan ? Whatever is default on the ramp type. Fan won`t go back in a breeze, `cos it doesn`t stop - at night it rolls down to 10% speed, then back up in the mornings.

Have you datalogged the supply to rule that out completely ? No - but the same supply line runs another drive to another fan - that one doesn`t fall over!

Like PLCs it's probably a simple fault and approachable without a laptop, either that or a duff drive.....Right. My thinking was that the dataset from the old drive might tell us something.

 

[kme]

Since the trips happen when fan is at, and continuing to rotate at, 100% speed (i.e. no speed change requests)

Then either inverter or supply..........

Thank you

 

[Sidewinder]

Could be an intermittent instantaneous cable or motor fault.

Think about open circuiting?

Also Siemens list an earth fault as a possibility for this fault on the MM420.

KME, what is the full model code?

This drive has been in for a few years now, so the motor has been running at 10% for long periods, perhaps there is now a "weakness" in the install?

 

[Sidewinder]

BTW, where does the speed command come from?

Just realised that I did not catch your whole description of the install.

We need to run through this again.

 

[kme]

Mmmmmmmm

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