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Negative Power numbers midway through run

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(@stevemck)
Posts: 8
Member
Topic starter
 

Trying to set up my single retarder eddy roller dyno and have been battling negative power figures midway through the run. Has anyone ran into this problem and if so any and all help would be appreciated. I've include .csv and .log of one of the logs as well as the saved options file

https://drive.google.com/drive/folders/168QNZQGGdHdMAFaSkJC1Q-RcLfJ_26NL?usp=sharing

 
Posted : 03/09/2021 7:19 am
(@stevemck)
Posts: 8
Member
Topic starter
 

Link was broken new link here

 
Posted : 04/09/2021 3:49 am
(@stevemck)
Posts: 8
Member
Topic starter
 

Admin ??

 
Posted : 06/09/2021 4:52 am
(@admin)
Posts: 1457
Member Admin
 

Hi. The load cell gets overloaded and the a/d converter wraps around to negative. You need a larger load cell.

 
Posted : 09/09/2021 7:25 pm
(@stevemck)
Posts: 8
Member
Topic starter
 

Hi admin thank you i will replace the load cell, can you give me some guidance on sizing.

Normally I am tuning or testing between 200 and 400 rw HP however have done mid 700 on this bed.

What KG option should I be ordering.

 

 
Posted : 10/09/2021 9:57 am
(@admin)
Posts: 1457
Member Admin
 

The best is to use the capacity of the brake to size the load cell. What brake is it? 

Calculate like this: 

Load cell size (kg) = Max brake torque (Nm) / 9.81 / load arm length (m). 

 
Posted : 10/09/2021 11:32 pm
(@stevemck)
Posts: 8
Member
Topic starter
 

I am using a Dyno Dynamics 450 bed. Finding specification for brake is challenging.

If I calculate like this 2200nm/9.81/430mm = 521.53

Assuming this is correct would I order the 500kg Load Cell or would I look at the 750kg

 

 
Posted : 11/09/2021 5:22 am
(@admin)
Posts: 1457
Member Admin
 

I would go for 750kg.

 
Posted : 11/09/2021 8:42 am
(@stevemck)
Posts: 8
Member
Topic starter
 

Thank you. Will do

 
Posted : 11/09/2021 9:01 am
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