M7s testing

<i>It remains to be seen whether anybody here realizes that the caps in all these inverters will require replacement as preventive maintenance. Don't bet your mortgage on it.
</i>

Oh man, this is gonna be so much fun to watch in another few years with all those M-7s running with dead cars. Hehehehehehe.

I'm sure someone will blame Mitsubishi for it, too...

I wonder how well the inverter does with dead caps? It might try its best, or it might just decide that things are too screwed up even try running.

Of course, they tend to drop off slowly at first, so I bet first you'll see cars with dead propulsion systems ("Stupid computer won't take power again!!!"), then as they get worse, lots of fun problems in the HVAC systems ("Stupid computer keeps turning things on and off randomly!")

Expect to hear a LOT of 'stupid computer!' problems when these things start failing. Everyone loves blaming the stupid computer, when it's generally NOT the computer at fault....

N340SG wrote:For those keeping track:

7475 and 7476 were being pushed into the yard as we were leaving work today. 202 more to go on this order.

Tom

Thanks.

Nasadowsk wrote:<i>It remains to be seen whether anybody here realizes that the caps in all these inverters will require replacement as preventive maintenance. Don't bet your mortgage on it.
</i>

Oh man, this is gonna be so much fun to watch in another few years with all those M-7s running with dead cars. Hehehehehehe.

I'm sure someone will blame Mitsubishi for it, too...

I wonder how well the inverter does with dead caps? It might try its best, or it might just decide that things are too screwed up even try running.

Of course, they tend to drop off slowly at first, so I bet first you'll see cars with dead propulsion systems ("Stupid computer won't take power again!!!"), then as they get worse, lots of fun problems in the HVAC systems ("Stupid computer keeps turning things on and off randomly!")

Expect to hear a LOT of 'stupid computer!' problems when these things start failing. Everyone loves blaming the stupid computer, when it's generally NOT the computer at fault....

I don't think so. Those M7s are running just fine. I doubt there is going to be dead cars in a few years.

Frank,

The point is that some preventive maintenance will need to be done, regardless of the quality of the parts. Electrolytic capacitors have a life expectancy. They do wear out. (Especially when your substations are spiking the heck out of them on a regular basis.)

Tom

N340SG wrote:Frank,

The point is that some preventive maintenance will need to be done, regardless of the quality of the parts. Electrolytic capacitors have a life expectancy. They do wear out. (Especially when your substations are spiking the heck out of them on a regular basis.)

Tom

I know that.

I know that.

I missed the winking smiley at the end of your post.

Tom

N340SG wrote:

I know that.

I missed the winking smiley at the end of your post.

Tom

Sorry! Here it is:

Wow -- youse are all the guyz who said I was in the stone age 'cause I like DC motors.

They just chew brushes and flash over. You can look at them with a flashlight and tell why they're blown up.

Replace capacitors??? The LIRR?? They woun't replace them until the blow a hole in the side of the stainless.

But we'll be gone by then -- I hope.

Clem

So Clem, you feel that in some cases the older technology had its advantages over the newer stuff? Hmmm; my Dad felt that way in the 1960's regarding stick shift cars vs. automatic transmissions. And the best telephone equipment I ever operated was an old plug-switchboard that was still in-service in the early 1980's. (Chuckle!) I missed out on that magneto-era equipment though.

Clem,

...I like DC motors.

They just chew brushes and flash over. You can look at them with a flashlight and tell why they're blown up

There is one other nifty thing that DC traction motors do.
When the pinion slips out between the motor and the gearcase, putting no load on the motor, a series- wound traction motor will accelerate until it self-destructs. It sounds like a jet engine until it lets go.
When you take the cover off one of these motors, it usually looks like a bird's nest in there.
You've probably seen at least one.

Tom

What's the max RPM on the various M series motors anyway? I know Budd experimented with 6500 (!) RPM ones on the Pioneer III cars, then went down to 5,000 something on the Silverliners, but I have nothing on the M cars

I guess the M-1s don't have any kind of feedback to detect a runaway motor. I'm not even sure how you do it with a DC system anyway.

Of course, an AC motor can't runaway at all, since it's speed is a function of the inverter's frequency...

What's the max RPM on the various M series motors anyway?

I'm not sure if that's listed anywhere in the manuals that I have. I'll get back to you on that only if I find something.

I guess the M-1s don't have any kind of feedback to detect a runaway motor.

Definitely not. The speed sensor is on the gearcase. If the motor mechanically disengages from the gearcase (slipped pinion) the gearcase will continue to roll at the speed of the train. But the motor, with no load on it now, cranks itself into oblivion.

I'm not even sure how you do it with a DC system anyway.

A speed sensor could have been mounted on the motor, with another on the gearcase. M-7s have that. On the M-1 and M-3, gearcase mounted speed sensors are only used for wheel slip/spin functions and ATC.

Tom

Yes, I've heard several slipped pinions, and had the pleasure of reaching the cut out switch somewhere around Woodhaven Station just in time for the motor armature to blow clear of its casing.

A memorable event, I must admit.

Clem

Speaking of M-7s, I saw 7479 and 7480 on the flatbeds in the yard today.
The EMU fleet is now roughly half M-7s (once those cars are tested and put into service, that is) and half M-1/M-3.
They muscled their way in, and henceforth will be the majority of the electric fleet.

Tom