MU connections ID?

This was labeled an FA1 1973, but... Can folks ID the numbered locations and use? Thanks.

Greetings

#1 is the 27 point trainline jumper

#2 650 volt single point trainline jumper-negative

#3 650 volt 4 point trainline jumper-positive

KRO52

kro52 wrote: ↑Sat Jun 22, 2019 7:13 am #1 is the 27 point trainline jumper
#2 650 volt single point trainline jumper-negative
#3 650 volt 4 point trainline jumper-positive

Thank you. Is the unit an FA1? Might the functions/description of these be defined for reference to non-railroad folks?

Greetings,

There is not enough picture to tell it is a FA1, suffice to say it is by the LIRR designation a PC6

KRO 52

#1: The 27 point trainline jumper was used to control the locomotive from the cab control / power-pack unit.

#2 and #3: The other two jumpers were for the 650 VDC Head End Power system, a system design unique to LIRR. Does anyone know the size of the four individual conductors in LIRR’s positive power trainline? For comparison, Amtrak uses twelve 4/0 (four ought) conductors in their 480 VAC HEP trainline.

You can see there is a fourth jumper located between #2 and #3. What was the function of that fourth jumper?

On #2 and #3, is there color coding, or different plug design, to prevent accidental attempts to plug negative into positive, or v.v.?

No color code,the 4 pin was the plus power,the single pin was the neg(ground) return
NO way to mix up the connections
The red color cover plate for the 27 point MU plug seems to be the standard at that time.

Thanks--I figured there had to be something.

Renumbered to add the #4 MU connection for description, sorry I missed it...
Anyone with color shots of this?

Thanks,Folks. #4 connection, as Jhdeasy asked? "...What was the function of that fourth jumper?..."

My speculation is that #4 could be a 27 pin connector used for a communications trainline. This could handle things like public address system, intercom, door control (open/close all doors at high level platform), etc.

Amtrak uses a 27 pin trainline connector for these features. It has a different pin arrangement than the MU trainline connector.

Hopefully a former LIRR employee who worked with this equipment or someone who owns a former LIRR P-75 push-pull car can answer this question.