Cable selection chart for motors ebook

Well, as the word LT Low Tension i. High Voltage or low torque and high torque respectively describe the whole story itself. This is the full load current cable needs to cater in Ideal condition. But in practical situation, there are several derating factors which need to be considered. If the ambient temp is greater than that, cable current carrying capacity derates.

Suppose our cable is in Air laid on cable tray,. Rating factors related to variation in ambient air temperature. If many cables are grouped together, they will all heat up. This will raise the temperature further. Hence we have to derate the current carrying capacity of the cable according to the grouping factor. Click to enlarge the table. Technical Details For 1. Current capacity of Sq. Total derating current of Sq. To decide Sq.

So in case of HT motor, the cable short circuit capacity alone is enough to determine the cable size as rest two parameters will automatically follow. Consider the below example:. Hence nearest higher size sq mm is required. We can see from the below table also that the short circuit capacity of sqmm cable is 28 KA which is more than our fault level. Click image to enlarge. Technical Details For 6.

We can see that this will automatically satisfy other two conditions also. Hence, the required cable shall able to carry minimum 15A current. Look at the Cable current rating Chart, 2. Here, we have collected for cable size for all rating motor such as, 0. Save my name, email, and website in this browser for the next time I comment.

Cable size calculator: Choose the three-phase motor capacity in HP. Choose Motor Power: 0. Torque conversion Calculation, Formula, Example. The Eng-Tips staff will check this out and take appropriate action. Click Here to join Eng-Tips and talk with other members! Already a Member? Join your peers on the Internet's largest technical engineering professional community. It's easy to join and it's free. Register now while it's still free!

Already a member? Close this window and log in. Join Us Close. Are you an Engineering professional? Join Eng-Tips Forums! Join Us! By joining you are opting in to receive e-mail. Promoting, selling, recruiting, coursework and thesis posting is forbidden. Students Click Here. Related Projects. But the actual current consumed by the motor is 23A.

When contacted the supplier they informed that this motor needs a 16mm cable. But earlier also we were using a 5HP pumpset different manufacturer with the same cable. The pumpset mentioned above is a replacement.

I need help in cable sizing. Can anyone of you explain is there any formula or how a cable sizing is actually made? For cable sizing there are usually two issues. One is ampacity of the cable. Too small cross sectional area of cable will cause overheating of the conductor and is a fire and other hazard. The insulation can actually melt. The other issue is voltage drop. Too much resistance causes the voltage to drop and you have less power available to your motor or other device.

For your case I would guess that you need to calculate voltage drop. I usually just use the Franklin Electric wire sizing chart for submersible motors.

They list wire size for , , , , and volts. You can get more accurate using voltage loss calculations but, this chart works well and saves a lot of time. The Franklin book also talks about using smaller wire sizes to eliminate the need for a soft starter with submersible motors. Quote from Franklin AIM manual; "Reduced-voltage starters may not be required if the maximum recommended cable length is used.

This may be enough reduction in starting current so that reduced-voltage starters are not required. This makes a "natural" soft start from Across The Line starters. Has anyone had experience with this before?