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Negative Power numbers midway through run

(@stevemck)
Member

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

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Topic starter Posted : 03/09/2021 6:19 am
(@stevemck)
Member

Link was broken new link here

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Topic starter Posted : 04/09/2021 2:49 am
(@stevemck)
Member

Admin ??

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Topic starter Posted : 06/09/2021 3:52 am
(@admin)
Member Admin

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

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Posted : 09/09/2021 6:25 pm
(@stevemck)
Member

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.

 

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Topic starter Posted : 10/09/2021 8:57 am
(@admin)
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). 

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Posted : 10/09/2021 10:32 pm
(@stevemck)
Member

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

 

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Topic starter Posted : 11/09/2021 4:22 am
(@admin)
Member Admin

I would go for 750kg.

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Posted : 11/09/2021 7:42 am
(@stevemck)
Member

Thank you. Will do

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Topic starter Posted : 11/09/2021 8:01 am
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