What voltage do you use?

Re: What voltage do you use?

Postby MacG » Mon Jul 06, 2015 12:56 pm

At DCC you can set the maximum voltage for the motor. It is CV5. I have a Tillig Digital Starter Set with the ESU Navigator. The power supply has 16V output, so I'm think, there are 15V at the rails. I have no problems at all.
Lok-n-Roll.de - we send worldwide :wink:
User avatar
MacG
 
Posts: 881
Images: 11
Joined: Mon Aug 15, 2011 1:19 pm
Location: Dresden, Germany

Re: What voltage do you use?

Postby dileTTante » Mon Jul 06, 2015 5:14 pm

Your experience is good to know about. However, while cv5 controls speed it doesn't change maximum voltage. At least that's the impression I have from reading about DCC.

From this page --- http://www.dccwiki.com/DCC_Power
we read this ---
"Remember, because there is full voltage on the rails at all times, there is also full voltage available at the power transistors at all times. If the transistors are turned on to pass all the available voltage, the loco will go at full speed. Unlike an analog DC train system, transistors are designed to pass full voltage, or no voltage, much like a fan switch. You either have full power, or no power. To control the speed, the decoder turns on and off the transistors hundreds, or thousands of times per second."

So, if you're running near maximum speed the DCC pulses leave full voltage on for a longer time than at lower speeds. If you run near maximum for a while your locomotive is getting a lot of full voltage. If you have set a lower speed maximum with CV5, the loco is still getting full voltage pulses spread out over a longer time with more zero voltage in between.

Other possible factors for motor burnout -- probably some motors are better than others, or some locomotives are harder to drive than others?

-Terry C.
dileTTante
 
Posts: 717
Joined: Wed Jan 06, 2010 12:37 am
Location: Vancouver British Columbia

Re: What voltage do you use?

Postby ConducTTor » Mon Jul 06, 2015 5:51 pm

dileTTante wrote:Other possible factors for motor burnout -- probably some motors are better than others, or some locomotives are harder to drive than others?

-Terry C.


Absolutely. Unfortunately those are factors that are hard or impossible to control.
What people think: "liberals/conservatives are ruining my country"
What the powerful know: divide and conquer
User avatar
ConducTTor
Site Admin
 
Posts: 8346
Images: 13
Joined: Sat May 23, 2009 4:52 pm
Location: Atlanta GA USA

Re: What voltage do you use?

Postby MacG » Tue Jul 07, 2015 3:41 pm

Okay, my source uses the wrong term voltage "Spannung". http://www.opendcc.de/info/decoder/dcc_cv.html

I have set no CV5 value at my locos. Except one with a MRC Sound Decoder, but this is because of the motor amp at the decoder. It over heated fast.
Lok-n-Roll.de - we send worldwide :wink:
User avatar
MacG
 
Posts: 881
Images: 11
Joined: Mon Aug 15, 2011 1:19 pm
Location: Dresden, Germany

Re: What voltage do you use?

Postby krokodil » Sat Jul 11, 2015 2:19 pm

Anyway use a solid switched power supply ( like for the computers etc), instead of transformers. On many switched power supplies you can adjust the output voltage what should be about 14V, than you can be sure that the motor wont get more than 12V. ( this is not the case with classic transformers - they can vary several volts depending of the current). Some DCC boosters ( central units) have internal stabilizers others do not. In such case the DCC power in the rails may vary. I like DCC control units which shows the voltage in the rails and the current - can be very useful.
On the other side, the DCC control is a PWM style power, which delivers much more power into the motors as you can do with standard DC control unit ( where you control the voltage in the tracks). This means for eg. at half speed in DC the motor gets only 6V, in DCC it will get 12 V square wave (50% on/off), what tends to overload the small motors ( overheat), therefor try to avoid long rides on half speed ( the most critical condition for the motors).
The PWM is ideal for slow speeds and for the range 75-100% of the max speed.
Greetings from Austria
E.T.
User avatar
krokodil
 
Posts: 495
Joined: Tue Jan 29, 2013 6:46 pm

Re: What voltage do you use?

Postby railtwister » Sat Jul 11, 2015 5:32 pm

Some DCC systems allow you to set the maximum output voltage while some may not. Digitrax has a three position toggle on their boosters that controls output voltage, using the setting marked N scale results in the lower output voltage, which should also be good for TT. Lowering the input voltage may not affect the total output voltage, but excess input voltage creates more heat as the system tries to keep things at the desired operating voltage.

Alex, were your units with burned out motors running with DCC decoders installed, or were you using the zero-stretching feature that some systems offer (though not MRC or NCE) that allows the system to control one non-decoder DC loco (mostly for testing)? Zero stretching is known to be hard on DC locos, especially if they are standing idle on active rails. I'm not sure about the SPROG, is yours a 2 or a 3? I have a SPROG 2, but I only use it for programming and testing decoder-equipped locos, so they usually don't stay on the track long enough to even get warm.

Bill in FtL
railtwister
 
Posts: 699
Images: 4
Joined: Sun Oct 04, 2009 8:39 am
Location: Oakland Park (Ft. Lauderdale), FL, USA

Re: What voltage do you use?

Postby ConducTTor » Sat Jul 11, 2015 10:34 pm

2 separate instances. One was 16v DC (no decoders), the other a Lenz DCC controller running off a 16v power supply. I don't know what 0 stretching is....My SPROG is a 2.
What people think: "liberals/conservatives are ruining my country"
What the powerful know: divide and conquer
User avatar
ConducTTor
Site Admin
 
Posts: 8346
Images: 13
Joined: Sat May 23, 2009 4:52 pm
Location: Atlanta GA USA

Re: What voltage do you use?

Postby krokodil » Sun Jul 12, 2015 2:22 am

16V DC is but too high. :angel:
Greetings from Austria
E.T.
User avatar
krokodil
 
Posts: 495
Joined: Tue Jan 29, 2013 6:46 pm

Re: What voltage do you use?

Postby railtwister » Sun Jul 12, 2015 9:41 am

ConducTTor wrote:2 separate instances. One was 16v DC (no decoders), the other a Lenz DCC controller running off a 16v power supply. I don't know what 0 stretching is....My SPROG is a 2.


Alex,

If the 16 volts is the output to the rails, that is a bit high for TT or N, but not drastically so for HO & larger. Zero stretching is the method used by Lenz and Digitrax to allow the operation of one non-decoder equipped loco on an otherwise DCC layout. It uses the address "00" for the DC loco, to which it sends balanced pulses of rapidly switching power to that address (almost like AC). By changing the balance of those pulses, the DC loco can be run at varying speeds in either direction. It works, and causes most motors to "buzz" or rattle, but will also cause overheating, especially in the idle position. For this reason it should only be used for testing a DC loco to make sure it runs before you install a decoder, or, at most, for short term running, no longer than a few minutes at a time. You should never allow the DC loco to sit stopped (as on a passing siding or at a station) for more than a few seconds, because that is when the worst overheating occurs. Some motors (usually the more expensive ones) are more sensitive to this problem than others. Neither NCE nor MRC offer the Zero Stretching feature in their DCC systems, nor does the SPROG as far as I know, although I've never looked into it to be sure.

Tony's Trains sells a digital meter that connects between the DCC output and the rails, because a regular meter can't get accurate readings due to the DCC signal. I'm not sure if this meter can be configured to read voltage, or just amperage. I don't know if the SPROG has it's own output voltage regulation, or if it is strictly dependent on input voltage.

I think for N and TT, a lower voltage closer to 12 volts would be better than 16 volts, since the motors used in TT seem closer to those used in N scale, rather than HO.

Bill in FtL
railtwister
 
Posts: 699
Images: 4
Joined: Sun Oct 04, 2009 8:39 am
Location: Oakland Park (Ft. Lauderdale), FL, USA

Re: What voltage do you use?

Postby ConducTTor » Sun Jul 12, 2015 10:50 am

Thanks guys. I bought 14v power supplies. With some loss between rails and wheels and decoder it should drop to around 12.5 at the motor.
What people think: "liberals/conservatives are ruining my country"
What the powerful know: divide and conquer
User avatar
ConducTTor
Site Admin
 
Posts: 8346
Images: 13
Joined: Sat May 23, 2009 4:52 pm
Location: Atlanta GA USA

PreviousNext

Return to Electric / DCC

Who is online

Users browsing this forum: No registered users and 0 guests