Motors in series

I am not convinced that wiring motors in series is the way to go. The engine will run slower, maybe closer to slow scale speeds, but you can do this by a throttle setting just as easily. My trains run fine just as they are.

The only thing I can add here, and I'm running conventional, is that when I converted an engine to series in addition to the slower starts, I get better smoke and lights at slower speeds because I'm putting more juice to the rails.

Does wiring in series cut the voltage in half? I'm not electrically charged.

 

Is it harder on the motor or does it matter? I know that low voltage is not good for some electronics.

GV, it does cut the voltage in half for a given transformer setting. Instead of the full 6 volts, say, at startup, each motor sees 3 volts. Its not until the transformer goes to 12 volts that each motor sees 6 volts.

A lot of folks are satisfied with the results but for me is poor engineering. There are better ways to slow a two motored engine down that don't compromise the effect of back EMF when the wheels slip.

 

Pete

What are those better ways?

Current inrush limiters that I have posted here many times for one. Dale Manquin's clever circuit for a second.

 

Pete

This is how I do it. I find it works best for me. I used it after throwing traction ties on some locos wired in series.

 

 Click to enlarge

 

Here are the advantages copied from another of my posts in reply to the same question asked here.

 

The diode dropper gives 4 volts less to the motor than it otherwise would have from track power. So the lights would have 4 more volts at a given speed.

 

At 18 volts throttle with series wiring each motor would get 9 volts. On a sharp curve the load would be uneven and voltage would not distribute evenly. The motors would not run evenly either.

 

At 18 volts throttle with the parallel wiring and voltage dropper, each motor would get 13 volts even counting the voltage drop of the bridge.

 

Thus the parallel wiring has more pulling power potential.

 

If the LED are hooked up as described they will burn at constant brightness from 6 to 18 volts on the throttle.

 

At 5 to 6 volts the motor would stall, you can stop the train, but the lights would stay on since they still have 5 volts. The engine lights are wired through the dropper which clamps the voltage.

 

Passneger cars with CV lighting would be left on also. So in conventional you could stop a train and leave the lights on. 

 

Here is a link on how to make the diode string

 

LINK

 

Dale H

Current inrush limiters only give you a slower start, they still don't give sustained slow speed running.

 

I'm not familiar with the circuit from Dale M. you mention, so I can't comment on that one.

 

 

 

 

Dale H. your circuit only allows single direction running as the bridge and diode configuration don't allow reverse.  That may be fine for some applications, but for many, I don't think it works.

 

John

 

See the link I added later for bi directional. The question in the other post was for forward only but the advantages are the same. The disadvantage is heat generated by the diodes. The lighting off the diode string is only an option,it can be made directional or bi directional or you can use a CL2-n3 chip  shown here 

 

LINK

 

Dale H

I don't see the bidirectional link.

 

My Williams 671 will maintain a fairly steady 3 MPH for a conventional engine when paced by an MTH engine. 

 

You can see Dale circuit in this thread. It compensates for the difference in back EMF when the wheels start to slip on one truck. For those not familiar when the wheels start to slip on one truck it also drops most of the voltage across that motor exacerbating the slipping. Not unlike a vehicle without a Limited slip differential putting all the power to the wheel that is spinning.

If you run short trains on level, clean track you may not see this happen. I would suggest anyone who runs long trains on grades should include Dale M's circuit if you wire the motors in series.

 

Pete

 

Sorry here it is

 

LINK

 

Dale H

 This is mostly an academic exercise for me, I run 99.9% command, so series wiring never comes up.

 

FWIW, when one motor loses traction with with back-EMF sensing, you tend to lose your traction as well.  Also, for Odyssey or other cruise control systems using a tach on one motor, if that motor loses traction, you're stuck as well.

 

There really is no such thing as a free lunch.

 

Tonight I did the series modification described in this thread to my WBB GP9. Wow! What a difference it makes. My question to the electrical experts: is there anything potentially harmful by running my loco at a crawl? FWIW, I use a WBB transformer, which has a range of 0-18v.

 

TIAA,

 

Matt

Some of our 2-rail brethren use a combination of series wiring with additional ballast in the locomotive. It prevents slipping while still presenting reduced current draw because the motors are in series.

I sure hope running slow isn't a problem, or I'm breaking a lot of locomotives!

 

Here's the thing I've always wondered about, because I have no electrical background whatsoever, if series wiring is so great why don't the manufacturers do it that way to begin with?

First guess?

Because kids like to run them FAST.

They do. Exhibit (A): K-Line. They provided a switch underneath near the reverse lockout switch to select series or parallel.

Some of you may know that real diesel locos such as GP-9s, RS-3s, etc. "transition" their truck-mounted traction motors from series, to series-parallel, and finally to full parallel operation for similar reasons.  Series provides maximum starting tractive effort, but to attain track speeds of 55 mph and above it's necessary to connect the multiple traction motors in parallel.  There are two steps because these locos have 4 motors, one per axle, vs. one per truck in our models.

 

Nowadays probably most DC-motored locos transition automatically at a preset speed (and I don't believe AC motored diesels transition at all.)  However in the early days I think the engineer or fireman had to initiate the transition at the proper speed by activating controls in the cab.

 

I would like to learn more about this process, but it would be best in a new post on the "Real Trains" area of the Forum.  -Ted

Not so if you have ever tried to run a Williams or K-Line diesel with a postwar ZW.

The need for series wiring is partially dictated by the minimum voltage of the specific transformer - the initial jolt to get the E-unit to cycle.  If you are running with a modern power controller (TPC, PowerMaster, etc.), you can ramp up from a lower voltage that allows lower speeds, in which case series wiring may not be necessary.

FWIW, I was testing my new Williams 44-ton locomotive, and I just configured the TIU to start the track voltage at 2 volts instead of the default 5 volts.  I got very good low speed performance with parallel wiring.

 

I found that if you are running WILLIAMS diesels from an MTH Z-4000 in conventional control, series wiring was the way to go.

And also FWIW...on my new LionChief + Pacific, using an ancient ZW for power, the thing will literally crawl at a snail's pace. A Williams U33C will do almost as well with conventional control. I personally don't see the need but to each his own.

Bingo! I use a 1033 with my Williams stuff and have never seen the need for series wiring. Alternately I can use my 135 Powermaster which also starts at zero volts.

 

Pete

  What is a I use a 1033 ..what is a 1033?

Lionel Post War transformer that has a tap that starts at zero volts which is what most transformers should do but most don't. It was included in many Post War sets.