Motor data 1

[redox]

I want some data on some old WRIM-motors we use in our plant, to check their settings. The manufacturer doesn't exist anymore, so I don't know where to obtain the data. Can I assume any values or is there any average value I can use for:

1. Safe hot stall time?
2. Permissible start attemps / hour?

The nameplate values of the motors is:

Power: 500kW; 450kW; 220kW; 200kW
rpm: 1483rpm; 495rpm; 1479rpm; 1497rpm
Stator V 3300V
Stator I 115A; 110V; 51.9A; 49A
Rotor V 855V; 613V; 399V; 390V
Rotor I 347A; 434A; 323A; 305A
Frequency 50Hz

Any help will be appreciated
Thanks
RCC

 

[aolalde]

My approach to your problem is based on average practices for motor design, which allows around 350 CM/Amp in copper conductor cross section at full load current.

Your permissible start attempts per hour will be related to the inrush current reduction achieved with the rotor resistive bank.

For inrush current reduction to 4.37 times Full load current, the winding will have 80 CM/Amp allowing around two starts in succession not longer than 20 seconds each per hour.

Further inrush current reduction will allow geometrical increase of starts. For instance if the inrush current is reduced to 2.18 times full load current, the winding will have 160 CM/Amp allowing 2 x ( 160/80)^2 = 8 starts in succession, and so on.

This is only speculation and you should do some trial test with the lower inrush current achievable, and then measure the winding temperature rise during and after every start, do not exceed 105°C since these are old motors with probably low insulation class.

 

[jbartos]

Question: Does a motor name plate still exist, when the manufacturer does not exist? Would it be possible to have the name plate data posted?

 

[redox]

Thanks for the replies.

jb:
The only nameplate data avaliable is the data in my first post.


There is 4 different size motors (Slipring motors, same manufacturer)
The only data again:

Motor 1
Power: 500kW
rpm: 1483rpm
Stator V: 3300V
Stator I: 115A
Rotor V: 855V
Rotor I: 347A
freq: 50Hz

Motor 2
Power: 450kW
rpm: 495rpm
Stator V: 3300V
Stator I: 110A
Rotor V: 613V
Rotor I: 434A
freq: 50Hz

Motor 3
Power: 220kW
rpm: 1479rpm
Stator V: 3300V
Stator I: 51.9A
Rotor V: 399V
Rotor I: 323A
freq: 50Hz

Motor 4
Power: 200kW
rpm: 1497rpm
Stator V: 3300V
Stator I: 49A
Rotor V: 390V
Rotor I: 305A
Frequency: 50Hz

 

[jbartos]

Comments marked ///\\\:
Motor 1
Power: 500kW
rpm: 1483rpm
Stator V: 3300V
Stator I: 115A
Rotor V: 855V
Rotor I: 347A
freq: 50Hz
///PF=500kW/(sqrt3 x 3.3kV x 115A)=0.76
is somewhat low for EFF assumed = 1. What has happened to the motor efficiency value? Is it unavailable or hard to read on the motor nameplate?\\Motor 2
Power: 450kW
rpm: 495rpm
Stator V: 3300V
Stator I: 110A
Rotor V: 613V
Rotor I: 434A
freq: 50Hz
///PF=450kW/(sqrt3 x 3.3 x 110A)=0.72 under assumed EFF=1\\Motor 3
Power: 220kW
rpm: 1479rpm
Stator V: 3300V
Stator I: 51.9A
Rotor V: 399V
Rotor I: 323A
freq: 50Hz
///PF=220kW/(sqrt3 x 3.3 x 51.9A)=0.74 under assumed EFF=1\\Motor 4
Power: 200kW
rpm: 1497rpm
Stator V: 3300V
Stator I: 49A
Rotor V: 390V
Rotor I: 305A
Frequency: 50Hz
///PF=200kW/(sqrt3 x 3.3 x 49A)=0.71 under assumed EFF=1\\\