Help me for selecting a AC motor!!!!!!

03 May 2008 12:08:55

thanh.tong

Dear all,
I'm doing my project in university. My project is to replace a DC
drive by a AC drive using inverter.
The old DC drive parameters are:
- Power 450kW
- Speed 50 to 1000r/min
(so Tn = 4298Nm) (Tn: nominal torque)
and the requirements are 250 % during 60 seconds acceleration and a
periodical overload of 160 percent during 30 seconds. That means I
need a starting torque is 250% nominal torque during 60 seconds.
(Ts = 2.5*Ts = 10745Nm)(Ts: starting torque)
Now I need to select an asynchronous motor to satisfy these
requirements but the problems are:
- The starting torque of AC motor is lesser than DC motor so I must
select a AC motor with larger power
AC motor : Ts = (1.5-2.5)Tn
So I must select AC motor power larger than DC motor to satisfy the
starting requirement.
I selected : P(AC motor) = 1.5 * P(DC motor) =675kW
So in AC drive I have:
motor power : P(AC) = 675kW
speed 1000r/min
Tn(AC) = 1.5 Tn(DC) = 6447Nm
Ts(AC) approximates 2*Tn(AC) = 12894Nm
They are my first draft calculations. Am I right?
Can you help me? and give me some advise.
I have searched on the internet an AC motor like that but I haven't
found any motor. If you have any information or help me find a motor
like that.
Look forward to hearing you soon.
Thanks

05 May 2008 05:10:49

www.interfacebus.com

Re: Help me for selecting a AC motor!!!!!!

On May 3, 3:08=A0pm, "thanh.tong" <thanhtongm...@gmail.com > wrote:
> Dear all,
> I'm doing my project in university. My project is to replace a DC
> drive by a AC drive using inverter.
> The old DC drive parameters are:
> - Power 450kW
> - Speed 50 to 1000r/min
> (so Tn =3D 4298Nm) (Tn: nominal torque)
> and the requirements are 250 % during 60 seconds acceleration and a
> periodical overload of 160 percent during 30 seconds. That means I
> need a starting torque is 250% nominal torque during 60 seconds.
> (Ts =3D 2.5*Ts =3D 10745Nm)(Ts: starting torque)
> Now I need to select an asynchronous motor to satisfy these
> requirements but the problems are:
> - The starting torque of AC motor is lesser than DC motor so I must
> select a AC motor with larger power
> AC motor : Ts =3D (1.5-2.5)Tn
> So I must select AC motor power larger than DC motor to satisfy the
> starting requirement.
> I selected : P(AC motor) =3D 1.5 * P(DC motor) =3D675kW
> So in AC drive I have:
> =A0 =A0motor power : P(AC) =3D 675kW
> =A0 =A0speed 1000r/min
> =A0 =A0Tn(AC) =3D 1.5 Tn(DC) =3D 6447Nm
> =A0 =A0Ts(AC) approximates 2*Tn(AC) =3D =A012894Nm
> They are my first draft calculations. Am I right?
> Can you help me? and give me some advise.
> I have searched on the internet an AC motor like that but I haven't
> found any motor. If you have any information or help me find a motor
> like that.
> Look forward to hearing you soon.
> Thanks

Here is a list of companies that manufacture motors;
http://www.interfacebus.com/motors.html