Motor Wattage, FLA, and Horsepower Automated Calculation

Questions about setting up and executing automated circuiting and regarding the use of the Circuit Manager and other circuiting tools.

Motor Wattage, FLA, and Horsepower Automated Calculation

Postby DeanUser » Fri Nov 26, 2010 5:00 pm

I noticed that the September 2010 release is automatically populating unfilled motor attributes when it can. This is great, since I am more than happy to let DraftLogic Electrical save me from having to manually calculate motor wattage, FLA, and horsepower. I will be much more comfortable, however, if I know what is going on and if is there anything I need to be aware of in regards to this new functionality?
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Re: Motor Wattage, FLA, and Horsepower Automated Calculation

Postby forumadmin » Mon Dec 13, 2010 12:32 am

Wow, nothing gets by you, Dean!

Yes, the September 2010 release included immense improvements to motor handling. This included:
a) making motor protection and conductor selection compliant with the base method of motor calculations in each of the CEC and NEC,
b) supporting usage of any single data element of load, horsepower, MCA, or FLA override to base the calculations upon,
c) extrapolating missing data elements from the most important of those provided, and
d) showing all different types of protection on the single line diagram (molded case breaker, fused disconnect, combination magnetic starter with fuse or breaker).

So all you have to do with a motor is populate any single one of load, horsepower, MCA, or FLA override prior to either running automated circuiting or using the Circuit Manager to circuit the motor. When you circuit it, the data elements that you did not populate will be filled with values extrapolated from what you did provide.

Here is the order of priority assigned to the data elements, the highest priority element you provide will be used:
1. Minimum Circuit Ampacity (MCA )
2. Maximum Overcurrent Protection (MOCP)
3. FLA Override (do not directly populate the Full Load Amps field, let DraftLogic Electrical manage that for you--use FLA Override to specify an FLA if you want to do choose one
4. Horsepower
5. Load (Watts)

Given any of the above, these attributes will be filled with extrapolated values if you didn't fill them already: Load, Horsepower, and Full Load Amps. Note this means that any value (correct, wrong, stale, anything!) in these attributes will prevent DraftLogic Electrical from calculating a value to fill them with.

Updating any of the specifications of a motor?

Update the data element(s) you are changing and empty out the remainder that are no longer correct and you want to be recalculated. Refer to the list of 1-5 above for what to ensure is either updated to a correct number or cleared to be filled with a new extrapolated value.

After updating the data elements, you will need to either run automated circuiting again or use the Circuit Manager to update the motor's protection. For a motor with an FLA greater than or equal to the cutoff you specified in your project settings, the feeder will be recalculated next time you run any schedule that triggers the Load Calculator (e.g. Panel Schedule, Single Line Diagram). For a motor with an FLA less than the cutoff you specified in your project settings, the feeder will be recalculated next time you run Automated Branch Circuit Wiring. If you are not making many changes and don't want to rerun Automated Branch Circuit Wiring, you can manually update the motor's conductors if they will change due to any protection change. Use the Branch Circuit Wire Manager if any BCW linework is involved and manually update the motor's Feeder Spec and home run block attributes as applicable.

Here is a screen capture of the motor attributes that have been referred to in this posting:

MotorAttributes_20101212.png (16.33 KiB) Viewed 18772 times
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