Induction motor class
Induction motor class
(OP)
I read an handbook about squirrel cage motor class. I am confusing with the explanation about class A, B,C and D induction motor. Could anybody explain to me the difference between them. Suppose I design a system with motor drived by VSD, should I consider this class?
Thanks you.
rgds,
pamungkas
Thanks you.
rgds,
pamungkas





RE: Induction motor class
http://www.manufacturing.net/ctl/article/CA188249?pubda...
David Baird
mrbaird@hotmail.com
Sr Controls Engineer
EET degree.
Journeyman Electrician.
RE: Induction motor class
The letters A, B, C, D might more likely correspond to the NEMA design letters which define the torque speed characterstics.
RE: Induction motor class
Motor nameplate also includes NEMA Code Letters the are closely linked to Locked-Rotor Current. See NFPA 70-2002 National Electrical Code
Table 430.7(B) Locked-Rotor Indicating Code Letters
Code Letter
Kilovolt-Amperes per
Horsepower with Locked
Rotor
A 0- 3.14
B 3.15 – 3.54
C 3.55 – 3.99
D 4.0 – 4.49
E 4.5 – 4.99
F 5.0 – 5.59
G 5.6 – 6.29
H 6.3 – 7.09
J 7.1 – 7.99
K 8.0 – 8.99
L 9.0 – 9.99
M 10.0 – 11.19
N 11.2 – 12.49
P 12.5 – 13.99
R 14.0 – 15.99
S 16.0 – 17.99
T 18.0 – 19.99
U 20.0 – 22.39
V 22.4 and up
RE: Induction motor class
I read an handbook about squirrel cage motor class. I am confusing with the explanation about class A, B,C and D induction motor. Could anybody explain to me the difference between them. Suppose I design a system with motor drived by VSD, should I consider this class?
///Assuming that the letters stand for the NEMA Design Letters, then they should be considered during a motor-VSD integration.\\\
RE: Induction motor class
Joseph... you state that the NEMA design letters should be consideed during a motor-VSD integration.....
But you neglect to tell us how they should be considered.
Would it not have been more helpful to state exactly how they should be considered....
Perhaps you'd care to enlighten us ...
Thank you
jΩ
RE: Induction motor class
http://search.netscape.com/ns/boomframe.jsp?query=%22vf...
for:
3.3.7 Motors for Variable Frequency Drive
and notice the motor - drive requirements. Also, check specification data sheets of VFDs.
Visit
http://search.netscape.com/ns/boomframe.jsp?query=%22de...
for:
By contrast, the Design E version of the same motor must have a nominal efficiency of 95.4 % and a minimum efficiency of 94.5 %, an appreciable improvement. In October of 1997, the federal energy efficiency legislation becomes effective and requires that replacement motors meet at least the minimum energy efficiency standards required for the "energy efficient" marking. Although this doesn't necessarily mean a Design E motor, such motors may often end up as the ones specified because of their greater efficiency. Be very careful, because often such motors cannot be used as horsepower-for-horsepower replacements. Even if the torque characteristics of the replacement motor will drive the load, as shown in subsequent portions of this article, the controller and the disconnect may not be able to handle the new motor.
\\\
RE: Induction motor class
This motor is operated in fixed speed (50 Hz) and DoL starting. In order to increase its utilization, we'll plan to operate in 2 mode for the future, 50 Hz and 25 Hz (in creep speed). Should I replace the motor or just add the appropriate VSD? note:
Motor spec:
3300 V Y 0.85 pf 405A
50 Hz 1475 rpm IMB3
104 A S Rotor IP55
480 kW 720 V
May someone told me the meaning of: S rotor 720 V 405A? Are these parameters same as lock rotor in NEMA?
Thanks for advanced!!
RE: Induction motor class
RE: Induction motor class
RE: Induction motor class
Nema Class A = 105degC, 65degC rise over ambient 40degC
Nema Class B = 130degC, 90degC rise over ambient 40degC
Nema Class F = 155degC, 115degC rise over ambient 40degC
Nema Class H = 180degC, 140degC rise over ambient 40degC
if the letter D is missing in here, then the Nema motor design letters A,B,C,D and missing E are more appropriate interpretation of the original posting.
RE: Induction motor class
The motor design does have an impact on VFD operation. For example, Design D has a high rotor resistance in order to shift the breakdown torque away from rated speed towards zero speed. This resistance generates more heat due to the harmonics impressed upon the motor due to the VFD. So there is a greater impact on motor life if the motor is design D vs Design B. Generally, Design C and D are not as well suited as Design B motors.
RE: Induction motor class
-pamungkas-
RE: Induction motor class
You can check this URL: http://www.sea.siemens.com/step/pdfs/acm_2.pdf
hope you 'll find what u need.
Mtchufi,bekasi
RE: Induction motor class
JB:
Joseph... you state that the NEMA design letters should be consideed during a motor-VSD integration.....
But you neglect to tell us how they should be considered.
Would it not have been more helpful to state exactly how they should be considered....
Perhaps you'd care to enlighten us ...
Thank you
///Please, may I inquire where is the eng-tip? I do not see it anywhere in your posting? What is this posting worth?\\\