Why do R62/A interior lights shut off periodically?

[RailRunRob]

If that's the case, since I think the longest 3rd rail gap is 200 ft, why do the lights dim or shut off, since on a 600 ft train, there's at least 3 cars/6 shoes touching the 3rd rail?

 

Where is this gap and does it happen on all types of trains crossing it?

My guess would that a certain point the voltage for the Train overall is only enough for the motors and reduced lighting system. HVAC might stop at a certain point if the available voltage drops. Also is the train coasting or accelerating across this gap that could play a part in some scenarios as well.

[danielhg121]

I think the wiring for some trains might be worse on some than others

 

 

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[RailRunRob]

I think the wiring for some trains might be worse on some than others

 

 

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It's probably just basic math Ohms law. In the bigger picture, The 600V we all know isn't anyways consistent it could be higher or lower depending on conditions is there another train pulling power on the power block? Could be a train putting power back in. Current flow vs potential energy the voltage potential is probably higher coming in. 650V/625V with nominal at 600V which is why when you see the specs for some cars you might see a higher voltage count. 

I'd bet if you ran the same train over that gap 10 times you probably get a different result maybe the light didn't dim one or two times. HVAC might turn off longer or shorter? Maybe there's two trains accelerating on the same power block next time maybe there's four? All depending. The motors will get priority. But the wiring is more on how the systems were designed and how they work together under different circumstances.

[B46 via Utica]

Both your reasons are wrong.

 

1) The carbody lights can shut off when passing over a 3rd rail gap leaving only the emergency lighting on for a few seconds(EX: passing over a switch) or when stopped over a switch basically a temporary loss of 600v to that car.

 

2) R62/A carbody lights are not LED

My apologies I will try to have better knowledge on stuff like this before I post. Thanks for the correction. Also, I've experience the lights shutting off because we hit a debris on an R62A before.

 

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[ttcsubwayfan]

While we're on the topic of trains' electrical systems, is the heating and air-conditioning fed directly from the third rail, or is it fed by the inverter/converter (or battery in the event of a failure)? I know that on a PCC streetcar, climate control comes from the 600 V system, but I'm not sure if there have been any technological advancements made since then that would allow them to be fed from the low voltage system.

[RailRunRob]

While we're on the topic of trains' electrical systems, is the heating and air-conditioning fed directly from the third rail, or is it fed by the inverter/converter (or battery in the event of a failure)? I know that on a PCC streetcar, climate control comes from the 600 V system, but I'm not sure if there have been any technological advancements made since then that would allow them to be fed from the low voltage system.

Inverter mainly from a APU/APS(Auxillary Power) inverter depending on the train.

[SubwayGuy]

oh boy...where to begin...

 

SMEE trains you have cars with converters. The converters convert 600VDC to 37.5VAC for the low voltage systems to use and the batteries to store. If a car with a converter comes off third rail and the batteries are low, the lights will dim as those cars "borrow" LV from the rest of the train to keep ONLY the emergency lights (above the doors) lit. On an R-46, these would be the doors in the high center ceiling of the car.

 

That's the easy part (answering the OP). Now to clear up MOST of the misinformation in this thread that has already been posted:

-low voltage from the converter used for propulsion is incapable of moving a train without 600VDC. the low voltage exists only to pass the commands from the master controller to the control group to move the 600v contacts that allow the train to take power. If it's off the rail, with fully charged batteries...it won't move (unless it's on a really nice hill and the brakes are released!) If some cars are on third rail, but not others, only the cars on the third rail will take power. The rest will just be along for the ride.

 

-low voltage can be (and is) trainlined but certain functions (main lights) are more local than others (emergency lights). This goes back to my answer for the original post. R62s do have a slightly different setup than R62As, which is why the lights do this more often on these cars. I'd rather not get into all the details, to keep this post short.

 

-A bad converter can also cause this. A car with working emergency lights only, even when on third rail...this is likely the cause.

 

-SMEE lights are fluorescent, not LED.

 

-"Hitting debris" has nothing to do with the carbody lights. In fact, that would never cause the lights to go out. This literally sounds like it was just made up. If it ever did happen, it was strictly coincidental. Short of hitting debris so big it knocked the converter or the battery box clean off the car, any electrical issue to cause lights out was present already before hitting any debris. It could have just put the train in emergency in a way the converter powering the lights in your car came off the third rail, and the lights went to emergency lights only after some time because of this.

 

-"Bad wiring" is not the issue. Again, this is just made up.

 

-Emergency lights only can indicate an issue with one or more cars in a set, but it's generally not enough to cause a breakdown unless all of the cars are affected (IE moving a married pair with dead batteries or no converter)

 

-Brakes are not dependent on having 600V power, but they rely on having trainline battery (37.5V) to electrically control all brakes in the consist at the same time. Without that, they'll apply and release reeeaaaalllyyyy sssssslllooooowwwwwlllyyyyyyyy. Which is why train operators and motormen are supposed to test the electric brake before moving.

 

-Trains are not powered by knife switches, but by 600V trolleys that pass through them. The purpose of the knife switch in those shop uses is to limit functionality of the train based on what maintenance personnel need. The most common position in shops is to deactivate propulsion etc. but allow for functioning converters and lights so that maintenance personnel can work.

 

-Leaving out anything to do with new tech to keep this short since it doesn't apply to the original post anyway. Just trying to clear up the (many) misconceptions and rampant speculating/assuming.

[RailRunRob]

oh boy...where to begin...

 

SMEE trains you have cars with converters. The converters convert 600VDC to 37.5VAC for the low voltage systems to use and the batteries to store. If a car with a converter comes off third rail and the batteries are low, the lights will dim as those cars "borrow" LV from the rest of the train to keep ONLY the emergency lights (above the doors) lit. On an R-46, these would be the doors in the high center ceiling of the car.

 

That's the easy part (answering the OP). Now to clear up MOST of the misinformation in this thread that has already been posted:

-low voltage from the converter used for propulsion is incapable of moving a train without 600VDC. the low voltage exists only to pass the commands from the master controller to the control group to move the 600v contacts that allow the train to take power. If it's off the rail, with fully charged batteries...it won't move (unless it's on a really nice hill and the brakes are released!) If some cars are on third rail, but not others, only the cars on the third rail will take power. The rest will just be along for the ride.

 

-low voltage can be (and is) trainlined but certain functions (main lights) are more local than others (emergency lights). This goes back to my answer for the original post. R62s do have a slightly different setup than R62As, which is why the lights do this more often on these cars. I'd rather not get into all the details, to keep this post short.

 

-A bad converter can also cause this. A car with working emergency lights only, even when on third rail...this is likely the cause.

 

-SMEE lights are fluorescent, not LED.

 

-"Hitting debris" has nothing to do with the carbody lights. In fact, that would never cause the lights to go out. This literally sounds like it was just made up. If it ever did happen, it was strictly coincidental. Short of hitting debris so big it knocked the converter or the battery box clean off the car, any electrical issue to cause lights out was present already before hitting any debris. It could have just put the train in emergency in a way the converter powering the lights in your car came off the third rail, and the lights went to emergency lights only after some time because of this.

 

-"Bad wiring" is not the issue. Again, this is just made up.

 

-Emergency lights only can indicate an issue with one or more cars in a set, but it's generally not enough to cause a breakdown unless all of the cars are affected (IE moving a married pair with dead batteries or no converter)

 

-Brakes are not dependent on having 600V power, but they rely on having trainline battery (37.5V) to electrically control all brakes in the consist at the same time. Without that, they'll apply and release reeeaaaalllyyyy sssssslllooooowwwwwlllyyyyyyyy. Which is why train operators and motormen are supposed to test the electric brake before moving.

 

-Trains are not powered by knife switches, but by 600V trolleys that pass through them. The purpose of the knife switch in those shop uses is to limit functionality of the train based on what maintenance personnel need. The most common position in shops is to deactivate propulsion etc. but allow for functioning converters and lights so that maintenance personnel can work.

 

-Leaving out anything to do with new tech to keep this short since it doesn't apply to the original post anyway. Just trying to clear up the (many) misconceptions and rampant speculating/assuming.

Thanks for this information. 

[RailRunRob]

oh boy...where to begin...

 

SMEE trains you have cars with converters. The converters convert 600VDC to 37.5VAC for the low voltage systems to use and the batteries to store. If a car with a converter comes off third rail and the batteries are low, the lights will dim as those cars "borrow" LV from the rest of the train to keep ONLY the emergency lights (above the doors) lit. On an R-46, these would be the doors in the high center ceiling of the car.

 

That's the easy part (answering the OP). Now to clear up MOST of the misinformation in this thread that has already been posted:

-low voltage from the converter used for propulsion is incapable of moving a train without 600VDC. the low voltage exists only to pass the commands from the master controller to the control group to move the 600v contacts that allow the train to take power. If it's off the rail, with fully charged batteries...it won't move (unless it's on a really nice hill and the brakes are released!) If some cars are on third rail, but not others, only the cars on the third rail will take power. The rest will just be along for the ride.

 

-low voltage can be (and is) trainlined but certain functions (main lights) are more local than others (emergency lights). This goes back to my answer for the original post. R62s do have a slightly different setup than R62As, which is why the lights do this more often on these cars. I'd rather not get into all the details, to keep this post short.

 

-A bad converter can also cause this. A car with working emergency lights only, even when on third rail...this is likely the cause.

 

-SMEE lights are fluorescent, not LED.

 

-"Hitting debris" has nothing to do with the carbody lights. In fact, that would never cause the lights to go out. This literally sounds like it was just made up. If it ever did happen, it was strictly coincidental. Short of hitting debris so big it knocked the converter or the battery box clean off the car, any electrical issue to cause lights out was present already before hitting any debris. It could have just put the train in emergency in a way the converter powering the lights in your car came off the third rail, and the lights went to emergency lights only after some time because of this.

 

-"Bad wiring" is not the issue. Again, this is just made up.

 

-Emergency lights only can indicate an issue with one or more cars in a set, but it's generally not enough to cause a breakdown unless all of the cars are affected (IE moving a married pair with dead batteries or no converter)

 

-Brakes are not dependent on having 600V power, but they rely on having trainline battery (37.5V) to electrically control all brakes in the consist at the same time. Without that, they'll apply and release reeeaaaalllyyyy sssssslllooooowwwwwlllyyyyyyyy. Which is why train operators and motormen are supposed to test the electric brake before moving.

 

-Trains are not powered by knife switches, but by 600V trolleys that pass through them. The purpose of the knife switch in those shop uses is to limit functionality of the train based on what maintenance personnel need. The most common position in shops is to deactivate propulsion etc. but allow for functioning converters and lights so that maintenance personnel can work.

 

-Leaving out anything to do with new tech to keep this short since it doesn't apply to the original post anyway. Just trying to clear up the (many) misconceptions and rampant speculating/assuming.

Hey just a question I don't really have too much experience with DC cars especially MTA rolling stock just wondering why 37.5VAC for Lo Volt and not VDC? with older cars? 

[ttcsubwayfan]

For the lights, at the very least, it would make more sense to have them run on AC power. From

 

 

 

Fluorescent lamps can run directly from a direct current (DC) supply of sufficient voltage to strike an arc. The ballast must be resistive, and would consume about as much power as the lamp. When operated from DC, the starting switch is often arranged to reverse the polarity of the supply to the lamp each time it is started; otherwise, the mercury accumulates at one end of the tube. Fluorescent lamps are (almost) never operated directly from DC for those reasons. Instead, an inverter converts the DC into AC and provides the current-limiting function as described below for electronic ballasts.

 

https://en.wikipedia.org/wiki/Fluorescent_lamp

 

I do not know whether the rest of the 37.5 V systems eat DC power or not.

[RailRunRob]

For the lights, at the very least, it would make more sense to have them run on AC power. From

 

 

 

 

https://en.wikipedia.org/wiki/Fluorescent_lamp

 

I do not know whether the rest of the 37.5 V systems eat DC power or not.

Yep, I understand the principals. But that makes sense. Just the Specs on newer trains have the Low volt on the DC side.  The APU (Auxiliary) is AC with subsystems there. Just wondering what's connecting to what. The stuff that I do know is on the newer side.

[SubwayGuy]

For the lights, at the very least, it would make more sense to have them run on AC power. From

 

 

 

 

https://en.wikipedia.org/wiki/Fluorescent_lamp

 

I do not know whether the rest of the 37.5 V systems eat DC power or not.

 

This is true about polarity. The older cars had a polarity reversing switch hidden behind the fuse panel for this purpose. Later "old" cars were set up to do it automatically but the switch remained as a fallback option.