Host Engineering Forum

General Category => Do-more CPUs and Do-more Designer Software => Topic started by: RBPLC on June 29, 2020, 06:21:41 PM

Title: Proper Fuse Sizing
Post by: RBPLC on June 29, 2020, 06:21:41 PM

What is considered the proper fuse size for a BX-DM1E-18ED23 unit on the input power leg to the controller? It looks like max inrush is 1.5A and is internally fused at 2.0A. I assume something like 1.6A is appropriate? 

Title: Re: Proper Fuse Sizing
Post by: ADC Product Engineer on July 01, 2020, 02:58:35 PM

The internal fuse is for UL.  It is unlikely that an external fuse will protect the PLC and the internal fuse will likely blow before the external fuse.  External fusing would only protect the wiring.

Title: Re: Proper Fuse Sizing
Post by: Garyhlucas on July 01, 2020, 06:20:10 PM

I fuse everything not just for protection but also for troubleshooting. At a previous job an entire waste water plant would have one control fuse. Something fails and blows the fuse and you had to start breaking wiring connections to find the problem. Lots of fuses and you know right where to look and most of your system stays running.