Karst and Bob
?
Thank you for your feedback on my question.
?
First, Bob could you share what brand circuit breakers you are using and how you have them setup (jumpers, CV settings, etc.)? ?We have been trying to use the NCE EB1 circuit breakers and the only way that they will trip before the DR5033 trips is if I set the DR5033 short circuit delay to 300ms - a setting of 225ms does not work.
?
Karst, you are correct, the need to circuit breakers is to minimize the effect of human error ?.? We do appreciate the fact that the DR5033 boosters, and the YD7001 and YD7403 handle what we call 'inrush current' - in one yard we can have 12 to 14 sound equipped locos sitting when the layout power goes on.
?
Karst, you said: ? Am I right, that the sole supply to that breaker is the Track-Out power from the booster ? If so, then there probably lies the problem: The YD7001/YD7403/DR5033 cut the power immediately ( within a single DCC packet's duration ) as soon as a short and/or overcurrent is detected.? They will then retry pulsing the power back on in about a 10ms time interval until the short-delay expires.
?
I am now wondering if I am getting into a race condition between the DR5033 and the NCE EB1.? By default the EB1 has a short circuit response time (delay time) of 16ms (it can be increased to 512ms).? I did a quick search on the NMRA site and it appears that a DCC packet's duration can be between 95 and 9900 microseconds, less than10 milliseconds.? Is it possible that the DR5033 is detecting the short before the EB1, and then it starts pulsing at 10ms intervals, which the EB1 cannot see as a short with its 16ms detection time? Further, since the DR5033 still sees a short when its circuit delay is reached, it signals a short and cuts the power.? If this is true, why does a setting of 300ms for the DR5033's short circuit delay allow the EB1 to detect the short before the DR5033?
?
I am testing on the workbench as follows:? Track output of DR5033 is set to 3 amps, and is directly attached to the DCC input of the EB1. EB1 is set to short at 2.2 amps. On the track output side of the EB1 I have an on/off toggle switch - turning the toggle to on creates the short.?
?
Jay Lennox - Toronto
?
Background on what we are now trying to do at York Railway Modellers:
?
- We have a large 40 foot x 40 foot (12 meter x 12 meter) layout room.? There are two main cities, Toronto and London, Ontario, Canada), with large yards that are connected by about 900 feet (275 meters) of mainline track plus passing sidings.? Each main city has a turntable and round house (we model 1955 during the steam to diesel transition period).
- There are 12 town and industrial yards along the main line - some have complex yard configurations that reflect what was in each town in 1955.
- The layout is powered by 7 DR5033's, and we have a YD7001 command station (it is not used to power the track). Breaking the layout into 7 power districts, was our start point when converting from DC to DCC in late 2019 and early 2020.
- The longer term plan was to add circuit breakers to introduce sub-power districts, probably for yards, as we gained experience with how to break up a DCC layout for operations.
- When we converted to DCC we had 8 members. We have almost doubled our membership in the last few years, and now on operations nights when someone runs a switch in a yard, others are impacted.??
- We are looking to move onto our longer term plan to add sub-power districts by using circuit breakers to isolate a yard from the mainline and other yards in the same power district.
?
