trying to understand 3 phase motor/capacitor installation

[qaz]

Capacitors need testing at full working voltage , in the case of 240 volts its about 400, a digital multi meter is not suitable.

i tested the cap with analogue meter as suggested in above post but will bear in mind what u say. was the test i did incorrect?
thanks

 

[M4SSO]

thanks, thats very interesting and obviously important, it might never have occurred to me.

as the speed control is by the cone [shown] i will just fit a single phase motor which will run continuously at one speed. if i can adapt it to the cradle [shown]

i want to thank everyone for their input, ive learned a lot from your comments
m

Newton Tesla in Warrington 01925 444773 still carry a range of single phase and three phase imperial frame size B56 motors they maybe able to help just give them the motor rating plate details

 

[qaz]

i will try them, thanks , but i suspect a new motor wikll be too expensive. what does imperial frame size B56 mean?

i tested the cap with analogue meter as suggested in above post but will bear in mind what u say. was the test i did incorrect?
thanks

 

[M4SSO]

thanks, thats very interesting and obviously important, it might never have occurred to me.

as the speed control is by the cone [shown] i will just fit a single phase motor which will run continuously at one speed. if i can adapt it to the cradle [shown]

i want to thank everyone for their input, ive learned a lot from your comments
m

Newton Tesla in Warrington 01925 444773 still carry a range of single phase and three phase imperial frame size B56 motors they maybe able to help just give them the motor rating plate details

i will try them, thanks , but i suspect a new motor wikll be too expensive. what does imperial frame size B56 mean?

i tested the cap with analogue meter as suggested in above post but will bear in mind what u say. was the test i did incorrect?
thanks

Motor frame sizes i.e. dimensions are given an alphanumeric code number in your case this is B56, the reason that it is an imperial frame size is because it was manufactured when we (the UK) worked in feet and inches, we now use the metric (SI) units in line with Europe.

If the motor insulation is damaged ( you said that it was smoking) I don't think you have any alternative but to replace the motor. You need to carry out continuity and insulation resistance tests on the motor before you can decide what the next step is, you will need an electrician to do this for you.

If the motor is deemed to be ok after these tests then in all likelihood it will be the capacitor which is at fault.

If you have to change the motor for one of a different kW rating you will probably have to change the overload relay in the starter control box to ensure the motor is protected correctly, again you will need an electrician to do this for you.

Testing a capacitor with an analogue meter (AVO) should be carried out as follows:-

Test a Capacitor By Analog AVO Multimeter
To check a capacitor by AVO (Ampere, voltage, Ohm Meter ), follow the following steps.

1. Make sure the suspected capacitor is fully discharged.
2. Take an AVO meter.
3. Select analog meter on OHM (Always, select the higher range of Ohms).
4. Connect the Meter leads to the Capacitor terminals.
5. Note The reading and Compare with the following results.
6. Short Capacitors: Shorted Capacitor will show very low Resistance.
7. Open Capacitors: An Open Capacitor will not show any movement (Deflection) on OHM meter Screen.
8. Good Capacitors: Initially, it will show low resistance, and then gradually increases toward the infinite. It means that Capacitor is in Good Condition.

Alternatively if you have a multimeter that reads capacitance

Checking Capacitor By Multimeter in the capacitance Mode
Note: You can do this test with a multimeter if you have a Capacitance meter or you have a multimeter with a feature to test the capacitance. Also, this method is good to test the tiny capacitors as well. To this test, rotate the multimeter knob to the capacitance mode.

1. Make sure the capacitor is fully discharged.
2. Remove the capacitors from board or circuit.
3. Now Select “Capacitance” on your multimeter.
4. Now connect the capacitor terminal to the multimeter leads.
5. If the reading is near to the actual value of the capacitor (i.e. the printed value on the Capacitor container box).
6. Then the capacitor is in good condition. (Note that the reading may be less than the actual value of the capacitor (the printed value on the Capacitor container box).
7. If you read a significantly lower capacitance or none at all, then capacitor is dead and you should change it.

 

[Steve000]

Some one on here should have warned you about capacitors and there ability to store and discharge energy. During my time as a railway signal technician in Australia. We used 3 phase motors wired to 110vac. These motors were used to open and close pedestrian gates to stop people walking across tracks when a train was coming. The motor would have 2 connections wired to live and another to neutral. The two lives would have 2 different capacitors giving dependant on which live was energised different direction running and different torque. The motor was able to still run at stall position but applying enough torque to hold the gate closed under pressure. I know I'm wasted no work in London for 2 months. Not sseen your set up but would suggest two speeds may have been available with this setup. Live via a capacitor and live without the capacitor in circuit. I'll try and look up the motor diagram to show how the private setup works but the manufacturer was magnetic controls in Australia. You might be able to find similarities .Steve

 

[qaz]

that test you describe is

Newton Tesla in Warrington 01925 444773 still carry a range of single phase and three phase imperial frame size B56 motors they maybe able to help just give them the motor rating plate details


Motor frame sizes i.e. dimensions are given an alphanumeric code number in your case this is B56, the reason that it is an imperial frame size is because it was manufactured when we (the UK) worked in feet and inches, we now use the metric (SI) units in line with Europe.

If the motor insulation is damaged ( you said that it was smoking) I don't think you have any alternative but to replace the motor. You need to carry out continuity and insulation resistance tests on the motor before you can decide what the next step is, you will need an electrician to do this for you.

If the motor is deemed to be ok after these tests then in all likelihood it will be the capacitor which is at fault.

If you have to change the motor for one of a different kW rating you will probably have to change the overload relay in the starter control box to ensure the motor is protected correctly, again you will need an electrician to do this for you.

Testing a capacitor with an analogue meter (AVO) should be carried out as follows:-

Test a Capacitor By Analog AVO Multimeter
To check a capacitor by AVO (Ampere, voltage, Ohm Meter ), follow the following steps.

1. Make sure the suspected capacitor is fully discharged.
2. Take an AVO meter.
3. Select analog meter on OHM (Always, select the higher range of Ohms).
4. Connect the Meter leads to the Capacitor terminals.
5. Note The reading and Compare with the following results.
6. Short Capacitors: Shorted Capacitor will show very low Resistance.
7. Open Capacitors: An Open Capacitor will not show any movement (Deflection) on OHM meter Screen.
8. Good Capacitors: Initially, it will show low resistance, and then gradually increases toward the infinite. It means that Capacitor is in Good Condition.

Alternatively if you have a multimeter that reads capacitance

Checking Capacitor By Multimeter in the capacitance Mode
Note: You can do this test with a multimeter if you have a Capacitance meter or you have a multimeter with a feature to test the capacitance. Also, this method is good to test the tiny capacitors as well. To this test, rotate the multimeter knob to the capacitance mode.

1. Make sure the capacitor is fully discharged.
2. Remove the capacitors from board or circuit.
3. Now Select “Capacitance” on your multimeter.
4. Now connect the capacitor terminal to the multimeter leads.
5. If the reading is near to the actual value of the capacitor (i.e. the printed value on the Capacitor container box).
6. Then the capacitor is in good condition. (Note that the reading may be less than the actual value of the capacitor (the printed value on the Capacitor container box).
7. If you read a significantly lower capacitance or none at all, then capacitor is dead and you should change it.

that test you describe is what i did

 

[qaz]

Some one on here should have warned you about capacitors and there ability to store and discharge energy. During my time as a railway signal technician in Australia. We used 3 phase motors wired to 110vac. These motors were used to open and close pedestrian gates to stop people walking across tracks when a train was coming. The motor would have 2 connections wired to live and another to neutral. The two lives would have 2 different capacitors giving dependant on which live was energised different direction running and different torque. The motor was able to still run at stall position but applying enough torque to hold the gate closed under pressure. I know I'm wasted no work in London for 2 months. Not sseen your set up but would suggest two speeds may have been available with this setup. Live via a capacitor and live without the capacitor in circuit. I'll try and look up the motor diagram to show how the private setup works but the manufacturer was magnetic controls in Australia. You might be able to find similarities .Steve

Steve, pls dont go to all that trouble of looking things up, im going to convert to single phase as its so simple and used motors are around

 

[qaz]

Newton Tesla in Warrington 01925 444773 still carry a range of single phase and three phase imperial frame size B56 motors they maybe able to help just give them the motor rating plate details


Motor frame sizes i.e. dimensions are given an alphanumeric code number in your case this is B56, the reason that it is an imperial frame size is because it was manufactured when we (the UK) worked in feet and inches, we now use the metric (SI) units in line with Europe.

does imperial frame size B56 indicate that the mounting bolt holes will be in same place as the old one [it fits into a cradle] [above photo]

 

[M4SSO]

When you tested the capacitor what conclusion did you arrive at, is the capacitor faulty or not, did you remove the resistor?
If you are changing the motor for a single phase unit then you won't need this capacitor the motor should have it's own?
A foot mounted imperial frame size B56 should fit but check the dimensions anyway, you will also need to check the overload in the starter box to ensure the replacement motor is protected correctly.

 

[qaz]

When you tested the capacitor what conclusion did you arrive at, is the capacitor faulty or not, did you remove the resistor?
If you are changing the motor for a single phase unit then you won't need this capacitor the motor should have it's own?
A foot mounted imperial frame size B56 should fit but check the dimensions anyway, you will also need to check the overload in the starter box to ensure the replacement motor is protected correctly.

i concluded it was ok , left resistor in place. thanks good news about the frame size. thanks

 

[M4SSO]

If you left the resistor in place for the test then you haven't tested the capacitor, you have tested the resistor!