Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

How can I size a cable for a motor?

Status
Not open for further replies.

mostafa0020

Member level 1
Joined
Oct 3, 2004
Messages
41
Helped
2
Reputation
4
Reaction score
0
Trophy points
1,286
Activity points
474
Hi all
How can i size a cable for a motor?i mean do i have to multiply the rated cuurent by a factor to compensate the starting current capacity heating for the cable?
 

Davood Amerion

Advanced Member level 2
Joined
Mar 1, 2005
Messages
584
Helped
116
Reputation
232
Reaction score
24
Trophy points
1,298
Location
Persia
Activity points
6,345
motor cable size

Hi;
as i know. we must use one parameter for determining of wire diameter.
this parameter known as 'J'.
J is current density in (eg.) copper wire.
J for copper wire is about 3-4 A/mm2 in transformer.
but we can use grater value, say 5-6, for other purposes.
this means for 3.14 Ampere current we need a 1mm
diameter wire (for J=4).

If your motor started 1 time in each (for ex.) 1 hour , you dont need use
thiker wire. but if your motor frequently started, you must increase wire size.
motor current in start condition reach about 10 times of
working its normal current.

Regards
davood
 

flatulent

Advanced Member level 5
Joined
Jul 19, 2002
Messages
4,629
Helped
489
Reputation
980
Reaction score
150
Trophy points
1,343
Location
Middle Earth
Activity points
46,689
motor cable sizes

The general rule for mains cables is that for lighting the voltage should drop by 2% or less zero to full load. For other loads 5% drop is acceptable.

With the present rising cost of electricity generating, it is probably more economical to pay for the larger diameter cable and save on operating costs by having more like 2% cable voltage drop for your motor.

You should also check the local laws about building wiring in your area. They may have more stringent requirements including the insulation type and possibly metal conduit covering for the cable routing and how many cables can be in a conduit. The source you purchased the motor from should be able to help you on this, or possibly the manufacturer of the motor.
 

IanP

Advanced Member level 5
Joined
Oct 5, 2004
Messages
7,942
Helped
2,311
Reputation
4,624
Reaction score
531
Trophy points
1,393
Location
West Coast
Activity points
66,416
cable sizing for motor

Here is "Wire sizing: a practical guide": **broken link removed**
You can apply formula used in this guide:
VDI = (AMPS x FEET)/(%VOLT DROP x VOLTAGE)
VDI = Voltage Drop Index (a reference number based on resistance of wire)
FEET = ONE-WAY wiring distance (1 meter = 3.28 feet)
%VOLT DROP = Your choice of acceptable voltage drop (example: use 3 for 3%)

Regards,
IanP
 

khongai

Full Member level 4
Joined
May 20, 2005
Messages
230
Helped
16
Reputation
32
Reaction score
11
Trophy points
1,298
Activity points
2,919
motor cable sizing

you may contact to ABB, Siemens, ... seller in your region to request that.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top