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DC Motor TEST Box

SCT27

Dec 5, 2017
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Dec 5, 2017
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Currently trying to make a test box with LED illumination for faster diagnosis.
The voltages are DC which range from 0v to 115v DRIVING DC motors.

I am using an LED driver:
http://docs-europe.electrocomponents.com/webdocs/132e/0900766b8132e7d9.pdf

Bridge Rectifier as the voltages change direction for the DC motor.

Also using this LED:
http://docs-europe.electrocomponents.com/webdocs/1395/0900766b813955e6.pdf

Ive fitted a Heat Sink to the driver but still finding it cooking at 50v and above.

Just ordered If anyone can suggest anything.......

Many Thanks
 

kellys_eye

Jun 25, 2010
6,514
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6,514
How does the LED assist in your diagnosis? Does it just 'light up'?

What form of heatsink did you fit? The tech sheet specifies an area of copper material (when pcb-mounted) such that the heat dissipation is via the limiter leads, not the case structure.
 

SCT27

Dec 5, 2017
2
Joined
Dec 5, 2017
Messages
2
Yes basically the LED just needs to Light so that we Can see where getting Voltage at the motor. There is limited working time in the area where the motor is installed.

Ive used the Heatsink below and this was attached to the casing:
https://uk.rs-online.com/web/p/heatsinks/5040716/

Not sure how it would be done via the limiter leads.?

The LED is 30mA. So @115 DC would be 3.45W(looking at the driver spec its 3w) Still getting very hot
at 60v
 

kellys_eye

Jun 25, 2010
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Fit a voltage limiting device across the LED arrangement (zener) to keep it within spec - say 30V.

Page 3 of the datasheet notes that for dissipation of around 2000mW (2W) you need a copper dissipation plane on the leads that equals of exceeds 500mm^2 on a 1oz or 2oz copper plane. The maximum dissipation is stated at 3000mW (3W).

AT 60V and 30mA you're at 1.8W and the heatsink requirement isn't being met.

Even at 1W (30V @ 30mA) you need up to 100mm^2 of copper but that's only a 10mm square!
 
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