03 May 2008 11:58:11

thanh.tong

Help me for select a AC motor

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 Tong,

03 May 2008 18:02:14

Jamie

Re: Help me for select a AC motor

thanh.tong 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 = 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 > Tong, Those calculations may hold true for a AC motor set up for Hz/V mode how ever, using them in Vector or Flux vector mode yields a lot of starting torque that is controlled very well.. -- http://webpages.charter.net/jamie_5"

14 May 2008 23:48:50

terry

Re: Help me for select a AC motor

On May 3, 8:02=A0pm, Jamie <jamie_ka1lpa_not_valid_after_ka1l...@charter.net > wrote: > thanh.tong 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 =A0 motor power : P(AC) =3D 675kW > > =A0 =A0 speed 1000r/min > > =A0 =A0 Tn(AC) =3D 1.5 Tn(DC) =3D 6447Nm > > =A0 =A0 Ts(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 > > Tong, > > Those calculations may hold true for a AC motor set up for Hz/V mode how > ever, using them in Vector or Flux vector mode yields a lot of starting > torque that is controlled very well.. > > --http://webpages.charter.net/jamie_5"-Hide quoted text - > > - Show quoted text - 450 kilowatt????? That's over 600 Horsepower? Large industrial!