[PRCo] Re: PCC Control

[Boris Cefer]

Yes, some of us are more crazy than others!

B

----- Original Message ----- 
From: "Bob Dietrich" <bdietrich at comcast.net>
To: <pittsburgh-railways at dementia.org>
Sent: Wednesday, May 16, 2007 12:58 AM
Subject: [PRCo] Re: PCC Control


> Holy cow Boris!  This is like listening in to a conversation between Dr.
> Fred and Dr. Allman.  I understand all the words; it is the combinations
> that throw me.
>
>
>
> -----Original Message-----
> From: pittsburgh-railways-bounce at lists.dementia.org
> [mailto:pittsburgh-railways-bounce at lists.dementia.org] On Behalf Of Boris
> Cefer
> Sent: Tuesday, May 15, 2007 12:48 PM
> To: pittsburgh-railways at dementia.org
> Subject: [PRCo] Re: PCC Control
>
> Yes, I am a bee...
>
> Well, what actually happened to you i do not know, but the car is expected
> to work this way:
>
> When you release power, one of the field shunting contactors (F2)
> immediately picks up to secure low-amp spotting of the motors and the
> accelerator. At higher speeds when the accelerator as at positions close 
> to
> the 99th finger, also other field shunting contactors are picked up (the
> usual arrangement is such that F1 picks up at 85th and F3 at 90th
> accelerator finger) to keep the spotting current at a reasonable value. 
> The
> overall accelerator resistance is something around 3.3 ohm and without 
> those
>
> field shunts applied above 85th the resistance would be absolutely
> insufficient and the spotting retardation would be pretty perceptible.
> By depressing brake pedal (just only to obtain brake) you remove part of
> these field shunts which builds up the dynamic braking current rapidly,
> practically without any movement of the accelerator rollers.
>
> The problem you are experiencing is very hard to judge - I need to get 
> under
>
> the car and see certain components to make a conclusion. I believe it 
> might
> be a limit relay problem. I think the limit relay of 1711 was modified to
> suit the back up controller.
>
> B
>
> ----- Original Message ----- 
> From: "Fred Schneider" <fwschneider at comcast.net>
> To: <pittsburgh-railways at dementia.org>
> Cc: "Orient Bernie" <bernieo22 at verizon.net>
> Sent: Tuesday, May 15, 2007 6:22 PM
> Subject: [PRCo] PCC Control
>
>
>> Boris:
>>
>> You bees the expert on this ...
>>
>> When I was running 1711 this weekend, I was bothered by an inability
>> to get the put my foot on the brake pedal lightly enough at almost
>> any speed to keep the dynamic brakes from coming on with a real
>> jolt.    It was especially rough at low speeds.   I know it isn't a
>> characteristic of all PCCs because I've never had the problem with
>> Baltimore Transit 7407; that car is much smoother.   Herb Brannon
>> commented that some PAT cars were that way and some were not, so it
>> must be either an adjustment or set up issue with the master
>> controller or a failure.   Are field shunts supposed to come in very
>> briefly in braking to cushion the initial application and then drop out?
>>
>> Fred
>>
>>
>>
>>
>>
>>
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>>
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>>
>>
>
>
>
>
>
>
> __________ Informace od NOD32 2262 (20070512) __________
>
> Tato zprava byla proverena antivirovym systemem NOD32.
> http://www.nod32.cz
>
>