How to test a DC Shunt motor ? What tests should be performed ?

[munzir]

How to test a DC Shunt motor ? What tests should be performed ?

 

[chuckey]

1. check its mechanically OK, bearings not seized, shaft not bent etc. 2. run it at full load . If it does not over heat its OK
Frank

 

[manishanand14]

Be careful not to run the DC Shunt Motor without supplying field current.



N=Speed in rpm
Phi=Field Flux

 

[munzir]

Electrically how to check and how to test ? Especially the field windings , armature windings & commutator and its segments etc . //???

 

[rfredel]

Hello munzir,

first test the field winding with a megohmmeter to check, that the winding has no short to the housing. Then check the current consumption of the field winding. If you can, start with a low voltage and rise it until you reach the nominal voltage. Look for the maximum current at the specification plate.If you reach the maximum current before the nominal voltage, the winding has a short.

For the armature first look if you can turn it easily. Then look for the brushes at the commutator. If they are good, put an ohmmeter at the connectors. Now turn the armature slowly by hand. If the armatur has no failure, every point of the commutator must have the same resistance.

After all tests are OK then you can put full voltage at the field winding and a variable Voltage to the armature. Now you can control the rotation of the armature by voltage.

Take care, that the field winding every time has full voltage, else your motor will rise up the rotation until it will explode.

I hope, I have say all, else ask me again.

Regards

Rainer

 

[munzir]

what do you mean by nominal voltage ?

Is this nominal voltage written on the nameplate of the motor ?

 

[rfredel]

Hello ,unzir,

yes, i named it nominal voltage. In German it is called "Nennspannung". I don't find a better translation.

Regards

Rainer

 

[munzir]

what actually a nominal voltage is ?

MAx. voltage or what ?

 

[rfredel]

Hello munzir,

I mean the voltage, what is written on the name plate of the motor.

The voltage for field (FLD.) and armature (ARM.) can be 110VDC, 220VDC or 440VDC for example. Also the amperage will be listed.

Regards

Raiiner

 

[dineshdeshmuk]

Variable voltage from 0V to what Volts ? what Volts AC or DC to the armature ?

What should happen when i slowly increase the voltage to the armature while the full voltage on field ?

 

[danishdeshmuk]

1. check its mechanically OK, bearings not seized, shaft not bent etc. 2. run it at full load . If it does not over heat its OK
Frank

What is the confirmation that the motor is not overheat ? how to get to know that ?

 

[rfredel]

Hello dineshdeshmuk,

Variable voltage from 0V to what Volts ?

Variable voltage from 0V to the max. voltage that's write on the name plate.

what Volts AC or DC to the armature ?

DC voltage, because it's a DC motor.

What should happen when i slowly increase the voltage to the armature while the full voltage on field ?

A shunt motor needs every time full field voltage, because if the field is gone and the armature has a voltage, the motor speed rise up until the motor will explode.
You can control the motor speed with the voltage of the armature.

If you want, I can send you a schematic of a speed control.

What is the confirmation that the motor is not overheat ? how to get to know that ?

If the windings have no short and you don't make a mechanical overload the motor can not overhead. To control this, measure the amperage.
Don't worry, if the motor gets warm under load. If you can touch it, it's OK.

Regards

Rainer

 

[munzir]

ye kindly send the schematic of a speed control for it

 

[rfredel]

Hello munzir, hello danishdeshmuk,

here I give you a circuit to control the speed of a DC Shunt motor.



Description:

S1 = Power switch to switch on

SW1 = Speed switch and starter switch for armature

SW2 = Speed switch for field winding

R1 to R9 = wirewound high power resistors

For the starting of the motor SW2 must be on position "0". With SW1 you can start the motor. Position "1" gives the lowest power to the armature and the lowest motor speed. Every next position will rise up the speed.
If you have a high power motor take care that this switch is on position "0" when you start it, else the motor take the highest power from line.
The resistors must have the same power capacity as the armature.

With SW2 you can make the motor speed higher than the nominal speed written on the name plate. To start the motor this switch must be on position "0". Every next position will make the speed higher. Take care the the field winding never lost contact to the line and the armature is online. This will kill your motor. The resistors must have the same power capacity as the field winding.

Regards

Rainer

 

[dineshdeshmuk]

can i have the circuit to control the speed of a series DC motor ?

 

[chuckey]

What you need is a variable DC power supply for this you need to know the ratings of the motor. Depending on the motors design a tachometer system should be included. As said before, running some sorts of series motors off load will lead them to over speed and self destruct, such as car starter motors and spin dryer motors, others such as electric drills, and angle grinders rely on the drag of the gear box to keep some load on the motor.
Frank

 

[rfredel]

Hello dineshdeshmuk,

Here is your circuit to control a DC series motor.



The resistors must have the same power as the motor. You can also use a adjustable DC voltage supply, that have the same power as the motor.

Regards

Rainer

 

[phatcreators]

can i have the circuit schematic of compound DC motor whether Commulative and differential ?

 

[rfredel]

Hello phatcreators,

here is your schematic.



To change the direction of the motor, change the polarity of the armature. To increase the speed higher then the nominal speed on the nameplate, you can drop the current in the shunt winding with S2.

All resistors must be high power resistors with the power of the winding.

Regards

Rainer

 

[munzir]

commulatively compounded & differentially compounded both types can be tested with this circuit , rfredel ?