Actualizacion EMCO VCM 300

[Oscar6]

Now I don't have a cable to connect the PC to the variator, I can see the data on the LCD of the variator, it says that you stop your motor in less than one resistance from 6000 rpm, you will have a braking one installed. Tomorrow try to check everything.

[Oscar6]

I have checked all the parameters and they all seem correct, it managed to go from 8000rpm to 0rpm in 10 seconds without error, using the 1000w 20ohm resistor, but after 9 seconds an ocd error appears, very high current, it may be due to the resistance of 20ohm, I would have to increase the ohms in a range of 43 ohms to 75 ohms as indicated in the table of my variator. Do you think that a 1500w50ohms resistor would work better? Another thing I have seen is the rpm on the variator at maximum speed reads 8160rpm at 272hz, on the motor plate it says 8000rpm at 272hz there is an error of 160rpm, I ask if this is normal .

[ashesman]

RPM = Hz x 120 / num poles = 272 x 120 / 4 = 8160 RPM

If you are getting over current then the resistance is probably too low. Stick within the value recommended by the book.

This motor must have a lot of rotating inertia to be that hard to slow down!
Either put

[Oscar6]

I imagine that the rpm are correct, I will ask for a resistance of 1500w40ohms, the inertia of my motor could be calculated by doing one for inertia. I have reviewed the parameters that you sent me of your drive and by doing tests I have detected that if in parameter 01.00 you set 400hz when the control sends maximum speed it will be for those hz even if it does not reach them due to the configuration of parameter 01.01, I imagine that your machine will reach the hz of parameter 01.01 long before setting it to maximum. For example, when the control requests a speed of 3000 rpm, the motor will rotate at 6000 rpm, when it requests 4000 rpm, the motor will continue at 6000 rpm. This is what my drive did with that configuration. hz, my control sends a 0v-10v signal, I don't know if yours will be the same.

[ashesman]

From memory, my motor is 8 pole so requires twice the frequency for the same RPM.

[Oscar6]

Hello again, I still have the problem of braking the spindle, today I tested a 40 ohm 1500w resistor, and the error is now high current, with 9 seconds of deceleration, I may have some wrong parameter in the drive, but no I know which one. I don't know if I have to modify any parameter of the DC current, or this DC current is only for the internal brake, I'm a little confused.

[ashesman]

The motor driver takes the AC mains and converts it to DC on its internal bus. Then it converts that DC to the driving AC for the motor at whatever frequency is required. During deceleration, the motor acts like a generator making AC. The drive converts that AC to DC current on to its internal bus. The DC bus capacitors can only charge so much before the voltage gets too high. At that point the braking resistor is applied to burn up the rest of the energy, keeping the DC bus at a safe value.

There are switches between the motor and dc bus and between the dc bus and brake resistor. Either of those could be going over current.

It seems your motor generates a lot of energy!

The answer will become obvious if you use the diagnostic tools available. Like the delta software for a PC. You can make a cable out of a cheap USB to RS-485 cable and and old ethernet patch cable. In the pc software you can graph the currents and volts in real time. And rpm and all sorts.

You can also display the parameters on the drive screen and watch them.

The drive error code you get will have a section in the manual explaining it. With recommendations on how to fix.

Just out of interest, how fast can the drive accelerate the motor? The current limit applies in both acceleration and deceleration.

Some drives require a bus bar link to be removed when waiting a braking resistor. Are you confident the resistor is working? A multi meter across the resistor terminals during braking will show if it works. Be careful as dangerous volts. You can also watch it in the PC software.

I can help you to make a cable if required. They are probably cheap to buy from delta, I havent looked.

[Oscar6]

The motor driver takes the AC mains and converts it to DC on its internal bus. Then it converts that DC to the driving AC for the motor at whatever frequency is required. During deceleration, the motor acts like a generator making AC. The drive converts that AC to DC current on to its internal bus. The DC bus capacitors can only charge so much before the voltage gets too high. At that point the braking resistor is applied to burn up the rest of the energy, keeping the DC bus at a safe value.

There are switches between the motor and dc bus and between the dc bus and brake resistor. Either of those could be going over current.

It seems your motor generates a lot of energy!

The answer will become obvious if you use the diagnostic tools available. Like the delta software for a PC. You can make a cable out of a cheap USB to RS-485 cable and and old ethernet patch cable. In the pc software you can graph the currents and volts in real time. And rpm and all sorts.

You can also display the parameters on the drive screen and watch them.

The drive error code you get will have a section in the manual explaining it. With recommendations on how to fix.

Just out of interest, how fast can the drive accelerate the motor? The current limit applies in both acceleration and deceleration.

Some drives require a bus bar link to be removed when waiting a braking resistor. Are you confident the resistor is working? A multi meter across the resistor terminals during braking will show if it works. Be careful as dangerous volts. You can also watch it in the PC software.

I can help you to make a cable if required. They are probably cheap to buy from delta, I havent looked.

Hello, I have the acceleration in automatic mode, and I would swear that it accelerates to maximum in about 3 seconds, the resistors are working because when you make several stops in a row you notice a little temperature but very little, I think that if everything was correctly configured the resistance should get hotter. Now it gives me an ocd error high current in deceleration. The problem with getting the PC connection cable is because of my location, if I order it it would take me a month to arrive. I don't know what to do. I will continue investigating or I could leave a list of parameters involved in braking.

[ashesman]

Just search usb rs-485 and you will find heaps of options. Then just cut up an old ethernet cable and wire it to it.

Braking resistors dont get very hot. They take a lot of repeated stops to get really hot

What is the exact error code so I can look it up in the manual.

Not sure about using automatic acceleration mode on a cnc. You sort of want to know the acceleration time so you can use it to delay between spindle start and cutting.

How much rotating mass is there on this motor?

Have you tried Delta technical support. I used the US support and they were pretty good.

If you could make a list of all the parameters you have changed it might help. I think there is a screen that shows all the modified parameters only.

[Oscar6]

The error is (ocd), the motor is connected to the spindle with a belt, there is nothing else. Do you know the link for the delta support.