Group: DynoMotion	Message: 9852	From: daveymahomh600e	Date: 7/26/2014
Subject: Losing Rectifier Modules

Hi Tom,

I have a Kflop/SnapAmp system running two 3 phase brushless servo motors on a lathe.

For some reason, every once in a while the rectifier in the power supply goes up in flames (okay not flames, just overheats to failure). The power supply is a 70Vdc capable of 35A and I have the SnapAmp clamp set at 80 and the peak current set to 11 (10 amps).

Any suggestions as to why the rectifier is overheating would be much appreciated.

Thank you,
David.

Group: DynoMotion	Message: 9853	From: Moray Cuthill	Date: 7/26/2014
Subject: Re: Losing Rectifier Modules

Does the rectifier have a suitable heatsink?

How warm does it get during normal use?

Assuming a standard forward voltage drop of 0.7V per diode, that's 1.4V nearly all the time when AC power is applied. So that's 14W of heat for every 10A you draw through it, which might not sound alot, but is more than enough to cook a poorly heatsinked bridge rectifier.

I've actually just checked the datasheet for the bridge rectifiers that I normally use, and they state a 1.1V drop per diode, so that's 22W per 10A.

Moray

On Sat, Jul 26, 2014 at 9:39 PM, david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

Hi Tom,

I have a Kflop/SnapAmp system running two 3 phase brushless servo motors on a lathe.

For some reason, every once in a while the rectifier in the power supply goes up in flames (okay not flames, just overheats to failure). The power supply is a 70Vdc capable of 35A and I have the SnapAmp clamp set at 80 and the peak current set to 11 (10 amps).

Any suggestions as to why the rectifier is overheating would be much appreciated.

Thank you,
David.

Group: DynoMotion	Message: 9854	From: David Stevenson	Date: 7/26/2014
Subject: Re: Losing Rectifier Modules

Hi Moray,

There is quite a good heatsink, but I'm not sure how hot it usually runs. Here is a link to the module ... http://www.antekinc.com/dc-80-rectifier-module/ and the rectifier is gooed to the aluminum back plate, which is screwed to the heavy aluminum plate of the main power supply.

Thanks for the information.

David

On 7/26/2014 6:00 PM, Moray Cuthill moray.cuthill@... [DynoMotion] wrote:

Does the rectifier have a suitable heatsink?

How warm does it get during normal use?

Assuming a standard forward voltage drop of 0.7V per diode, that's 1.4V nearly all the time when AC power is applied. So that's 14W of heat for every 10A you draw through it, which might not sound alot, but is more than enough to cook a poorly heatsinked bridge rectifier.

I've actually just checked the datasheet for the bridge rectifiers that I normally use, and they state a 1.1V drop per diode, so that's 22W per 10A.

Moray

On Sat, Jul 26, 2014 at 9:39 PM, david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

Hi Tom,

I have a Kflop/SnapAmp system running two 3 phase brushless servo motors on a lathe.

For some reason, every once in a while the rectifier in the power supply goes up in flames (okay not flames, just overheats to failure). The power supply is a 70Vdc capable of 35A and I have the SnapAmp clamp set at 80 and the peak current set to 11 (10 amps).

Any suggestions as to why the rectifier is overheating would be much appreciated.

Thank you,
David.

Group: DynoMotion	Message: 9855	From: Moray Cuthill	Date: 7/26/2014
Subject: Re: Losing Rectifier Modules

That link would explain why you said module, as I normally use seperate parts so assumed you meant a bridge rectifier.

What exactly is going up in smoke?

Also, have you checked the voltages that things are running at?

Moray

On Sat, Jul 26, 2014 at 11:24 PM, David Stevenson david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

Hi Moray,

There is quite a good heatsink, but I'm not sure how hot it usually runs. Here is a link to the module ... http://www.antekinc.com/dc-80-rectifier-module/ and the rectifier is gooed to the aluminum back plate, which is screwed to the heavy aluminum plate of the main power supply.

Thanks for the information.

David

On 7/26/2014 6:00 PM, Moray Cuthill moray.cuthill@... [DynoMotion] wrote:

Does the rectifier have a suitable heatsink?

How warm does it get during normal use?

Assuming a standard forward voltage drop of 0.7V per diode, that's 1.4V nearly all the time when AC power is applied. So that's 14W of heat for every 10A you draw through it, which might not sound alot, but is more than enough to cook a poorly heatsinked bridge rectifier.

I've actually just checked the datasheet for the bridge rectifiers that I normally use, and they state a 1.1V drop per diode, so that's 22W per 10A.

Moray

On Sat, Jul 26, 2014 at 9:39 PM, david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

Hi Tom,

I have a Kflop/SnapAmp system running two 3 phase brushless servo motors on a lathe.

For some reason, every once in a while the rectifier in the power supply goes up in flames (okay not flames, just overheats to failure). The power supply is a 70Vdc capable of 35A and I have the SnapAmp clamp set at 80 and the peak current set to 11 (10 amps).

Any suggestions as to why the rectifier is overheating would be much appreciated.

Thank you,
David.

Group: DynoMotion	Message: 9856	From: David Stevenson	Date: 7/26/2014
Subject: Re: Losing Rectifier Modules

The rectifier is burning the soldier joints where it passes through the circuit board.

I haven't check the voltages, but the output of the module is usually in the high 60 volts area. I thought that the SnapAmp managed the values.

Thanks,
David.

On 7/26/2014 6:31 PM, Moray Cuthill moray.cuthill@... [DynoMotion] wrote:

That link would explain why you said module, as I normally use seperate parts so assumed you meant a bridge rectifier.

What exactly is going up in smoke?

Also, have you checked the voltages that things are running at?

Moray

On Sat, Jul 26, 2014 at 11:24 PM, David Stevenson david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

Hi Moray,

There is quite a good heatsink, but I'm not sure how hot it usually runs. Here is a link to the module ... http://www.antekinc.com/dc-80-rectifier-module/ and the rectifier is gooed to the aluminum back plate, which is screwed to the heavy aluminum plate of the main power supply.

Thanks for the information.

David

On 7/26/2014 6:00 PM, Moray Cuthill moray.cuthill@... [DynoMotion] wrote:

Does the rectifier have a suitable heatsink?

How warm does it get during normal use?

Assuming a standard forward voltage drop of 0.7V per diode, that's 1.4V nearly all the time when AC power is applied. So that's 14W of heat for every 10A you draw through it, which might not sound alot, but is more than enough to cook a poorly heatsinked bridge rectifier.

I've actually just checked the datasheet for the bridge rectifiers that I normally use, and they state a 1.1V drop per diode, so that's 22W per 10A.

Moray

On Sat, Jul 26, 2014 at 9:39 PM, david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

Hi Tom,

I have a Kflop/SnapAmp system running two 3 phase brushless servo motors on a lathe.

For some reason, every once in a while the rectifier in the power supply goes up in flames (okay not flames, just overheats to failure). The power supply is a 70Vdc capable of 35A and I have the SnapAmp clamp set at 80 and the peak current set to 11 (10 amps).

Any suggestions as to why the rectifier is overheating would be much appreciated.

Thank you,
David.

Group: DynoMotion	Message: 9857	From: Moray Cuthill	Date: 7/26/2014
Subject: Re: Losing Rectifier Modules

I did wonder if the PCB was designed to handle the current involved.

Personally, I'd swap it out for individual components.

If the 20'000uF has been working for you, get a single large capacitor with screw/spade terminals (makes connections far simpler that solder terminals), a suitable bridge rectifer (with spade terminals), and a suitable bleed resistor. The bleed resistor should be connected over the capacitor terminals so it drains the capacitor when power is removed and there is no load applied. Something like a 1kOhm 10W resistor will lower the voltage in under a minute.

Wire it so the resistor is the star-point in the power circuit i.e. the output from the bridge rectifier connects to the capacitor, then everything that is needs power is also connected to the capacitor.

Bolt the bridge rectifier either to a suitable chunk of aluminium, or possibly your control box with some heat paste, and monitor how hot it gets. I've never had to use a proper bridge rectifier heatsink, however that may be an option for your setup.

The individual components may cost more, however at least if something does go pop, it'll be far cheaper to replace.

Moray

On Sat, Jul 26, 2014 at 11:38 PM, David Stevenson david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

The rectifier is burning the soldier joints where it passes through the circuit board.

I haven't check the voltages, but the output of the module is usually in the high 60 volts area. I thought that the SnapAmp managed the values.

Thanks,
David.

On 7/26/2014 6:31 PM, Moray Cuthill moray.cuthill@... [DynoMotion] wrote:

That link would explain why you said module, as I normally use seperate parts so assumed you meant a bridge rectifier.

What exactly is going up in smoke?

Also, have you checked the voltages that things are running at?

Moray

On Sat, Jul 26, 2014 at 11:24 PM, David Stevenson david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

Hi Moray,

There is quite a good heatsink, but I'm not sure how hot it usually runs. Here is a link to the module ... http://www.antekinc.com/dc-80-rectifier-module/ and the rectifier is gooed to the aluminum back plate, which is screwed to the heavy aluminum plate of the main power supply.

Thanks for the information.

David

On 7/26/2014 6:00 PM, Moray Cuthill moray.cuthill@... [DynoMotion] wrote:

Does the rectifier have a suitable heatsink?

How warm does it get during normal use?

Assuming a standard forward voltage drop of 0.7V per diode, that's 1.4V nearly all the time when AC power is applied. So that's 14W of heat for every 10A you draw through it, which might not sound alot, but is more than enough to cook a poorly heatsinked bridge rectifier.

I've actually just checked the datasheet for the bridge rectifiers that I normally use, and they state a 1.1V drop per diode, so that's 22W per 10A.

Moray

On Sat, Jul 26, 2014 at 9:39 PM, david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

Hi Tom,

I have a Kflop/SnapAmp system running two 3 phase brushless servo motors on a lathe.

For some reason, every once in a while the rectifier in the power supply goes up in flames (okay not flames, just overheats to failure). The power supply is a 70Vdc capable of 35A and I have the SnapAmp clamp set at 80 and the peak current set to 11 (10 amps).

Any suggestions as to why the rectifier is overheating would be much appreciated.

Thank you,
David.

Group: DynoMotion	Message: 9858	From: David Stevenson	Date: 7/26/2014
Subject: Re: Losing Rectifier Modules

I really only have a basic understanding of electronics, so when I was introduced to the power supplies from Antek they seemed like a good solution. The module that went today is the second one to do that, so maybe I need to explore some other options. How would one determine what a suitable bridge rectifier is?

Thanks for your help Moray.

Best regards,
David.

On 7/26/2014 6:54 PM, Moray Cuthill moray.cuthill@... [DynoMotion] wrote:

I did wonder if the PCB was designed to handle the current involved.

Personally, I'd swap it out for individual components.

If the 20'000uF has been working for you, get a single large capacitor with screw/spade terminals (makes connections far simpler that solder terminals), a suitable bridge rectifer (with spade terminals), and a suitable bleed resistor. The bleed resistor should be connected over the capacitor terminals so it drains the capacitor when power is removed and there is no load applied. Something like a 1kOhm 10W resistor will lower the voltage in under a minute.

Wire it so the resistor is the star-point in the power circuit i.e. the output from the bridge rectifier connects to the capacitor, then everything that is needs power is also connected to the capacitor.

Bolt the bridge rectifier either to a suitable chunk of aluminium, or possibly your control box with some heat paste, and monitor how hot it gets. I've never had to use a proper bridge rectifier heatsink, however that may be an option for your setup.

The individual components may cost more, however at least if something does go pop, it'll be far cheaper to replace.

Moray

On Sat, Jul 26, 2014 at 11:38 PM, David Stevenson david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

The rectifier is burning the soldier joints where it passes through the circuit board.

I haven't check the voltages, but the output of the module is usually in the high 60 volts area. I thought that the SnapAmp managed the values.

Thanks,
David.

On 7/26/2014 6:31 PM, Moray Cuthill moray.cuthill@... [DynoMotion] wrote:

That link would explain why you said module, as I normally use seperate parts so assumed you meant a bridge rectifier.

What exactly is going up in smoke?

Also, have you checked the voltages that things are running at?

Moray

On Sat, Jul 26, 2014 at 11:24 PM, David Stevenson david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

Hi Moray,

There is quite a good heatsink, but I'm not sure how hot it usually runs. Here is a link to the module ... http://www.antekinc.com/dc-80-rectifier-module/ and the rectifier is gooed to the aluminum back plate, which is screwed to the heavy aluminum plate of the main power supply.

Thanks for the information.

David

On 7/26/2014 6:00 PM, Moray Cuthill moray.cuthill@... [DynoMotion] wrote:

Does the rectifier have a suitable heatsink?

How warm does it get during normal use?

Assuming a standard forward voltage drop of 0.7V per diode, that's 1.4V nearly all the time when AC power is applied. So that's 14W of heat for every 10A you draw through it, which might not sound alot, but is more than enough to cook a poorly heatsinked bridge rectifier.

I've actually just checked the datasheet for the bridge rectifiers that I normally use, and they state a 1.1V drop per diode, so that's 22W per 10A.

Moray

On Sat, Jul 26, 2014 at 9:39 PM, david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

Hi Tom,

I have a Kflop/SnapAmp system running two 3 phase brushless servo motors on a lathe.

For some reason, every once in a while the rectifier in the power supply goes up in flames (okay not flames, just overheats to failure). The power supply is a 70Vdc capable of 35A and I have the SnapAmp clamp set at 80 and the peak current set to 11 (10 amps).

Any suggestions as to why the rectifier is overheating would be much appreciated.

Thank you,
David.

Group: DynoMotion	Message: 9861	From: Moray Cuthill	Date: 7/27/2014
Subject: Re: Losing Rectifier Modules

For a bridge rectifier, you just need to select a suitable current/voltage/case for your required application.

I'm UK based, so I'm hoping somebody from your side of the pond will post some recommendations for suppliers.

Moray

On Sun, Jul 27, 2014 at 12:32 AM, David Stevenson david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

I really only have a basic understanding of electronics, so when I was introduced to the power supplies from Antek they seemed like a good solution. The module that went today is the second one to do that, so maybe I need to explore some other options. How would one determine what a suitable bridge rectifier is?

Thanks for your help Moray.

Best regards,
David.

On 7/26/2014 6:54 PM, Moray Cuthill moray.cuthill@... [DynoMotion] wrote:

I did wonder if the PCB was designed to handle the current involved.

Personally, I'd swap it out for individual components.

If the 20'000uF has been working for you, get a single large capacitor with screw/spade terminals (makes connections far simpler that solder terminals), a suitable bridge rectifer (with spade terminals), and a suitable bleed resistor. The bleed resistor should be connected over the capacitor terminals so it drains the capacitor when power is removed and there is no load applied. Something like a 1kOhm 10W resistor will lower the voltage in under a minute.

Wire it so the resistor is the star-point in the power circuit i.e. the output from the bridge rectifier connects to the capacitor, then everything that is needs power is also connected to the capacitor.

Bolt the bridge rectifier either to a suitable chunk of aluminium, or possibly your control box with some heat paste, and monitor how hot it gets. I've never had to use a proper bridge rectifier heatsink, however that may be an option for your setup.

The individual components may cost more, however at least if something does go pop, it'll be far cheaper to replace.

Moray

On Sat, Jul 26, 2014 at 11:38 PM, David Stevenson david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

The rectifier is burning the soldier joints where it passes through the circuit board.

I haven't check the voltages, but the output of the module is usually in the high 60 volts area. I thought that the SnapAmp managed the values.

Thanks,
David.

On 7/26/2014 6:31 PM, Moray Cuthill moray.cuthill@... [DynoMotion] wrote:

That link would explain why you said module, as I normally use seperate parts so assumed you meant a bridge rectifier.

What exactly is going up in smoke?

Also, have you checked the voltages that things are running at?

Moray

On Sat, Jul 26, 2014 at 11:24 PM, David Stevenson david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

Hi Moray,

There is quite a good heatsink, but I'm not sure how hot it usually runs. Here is a link to the module ... http://www.antekinc.com/dc-80-rectifier-module/ and the rectifier is gooed to the aluminum back plate, which is screwed to the heavy aluminum plate of the main power supply.

Thanks for the information.

David

On 7/26/2014 6:00 PM, Moray Cuthill moray.cuthill@... [DynoMotion] wrote:

Does the rectifier have a suitable heatsink?

How warm does it get during normal use?

Assuming a standard forward voltage drop of 0.7V per diode, that's 1.4V nearly all the time when AC power is applied. So that's 14W of heat for every 10A you draw through it, which might not sound alot, but is more than enough to cook a poorly heatsinked bridge rectifier.

I've actually just checked the datasheet for the bridge rectifiers that I normally use, and they state a 1.1V drop per diode, so that's 22W per 10A.

Moray

On Sat, Jul 26, 2014 at 9:39 PM, david.m.stevenson@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:

Hi Tom,

I have a Kflop/SnapAmp system running two 3 phase brushless servo motors on a lathe.

For some reason, every once in a while the rectifier in the power supply goes up in flames (okay not flames, just overheats to failure). The power supply is a 70Vdc capable of 35A and I have the SnapAmp clamp set at 80 and the peak current set to 11 (10 amps).

Any suggestions as to why the rectifier is overheating would be much appreciated.

Thank you,
David.

Group: DynoMotion	Message: 9862	From: Tom Kerekes	Date: 7/27/2014
Subject: Re: Losing Rectifier Modules

Hi David,

What was going on when the supply blew? Had you been driving the motors hard just before? Sitting idle? Just switched on power?

Regards

Group: DynoMotion	Message: 9867	From: David Stevenson	Date: 7/27/2014
Subject: Re: Losing Rectifier Modules

Hi Tom,

I had just switched on the system and was going to do some computer file work. The system had been homed and was basically just sitting idle.

Thanks,
David.

On 7/27/2014 8:34 AM, Tom Kerekes tk@... [DynoMotion] wrote:

Hi David,

What was going on when the supply blew? Had you been driving the motors hard just before? Sitting idle? Just switched on power?

Regards

TK

Group: DynoMotion Message: 9868 From: Tom Kerekes Date: 7/27/2014

Subject: Re: Losing Rectifier Modules

Hi David,

In that case there should be very little power draw from the supply. Something improper must be going on. Could the system have homed improperly? Maybe driving continuously against the hard stop?

Did both failure happen in the same manner?

You might add a fuse. Maybe 20Amps.

Regards
TK

Group: DynoMotion Message: 9870 From: David Stevenson Date: 7/27/2014

Subject: Re: Losing Rectifier Modules

Hi Tom,

I couldn't find anything obviously wrong. I can't recall exactly, but I believe I even moved the slide slightly out of the home position with the gamepad because I prefer it slightly inside the ballpark in case something goes astray.

With regard to the previous failure, I was moving the slide when it stopped responding, but I thought I couldn't overload it with the settings being what they are and the capacity of the power supply. Apparently that's not the case.

I do have a breaker in the cabinet now. It was added after the previous failure. The breaker kicked out this time, but there is a dead short or something else wrong in the DC module of the power supply. There are signs of heating on the soldered terminals of the rectifier.

Thanks for your help,
David.

On 7/27/2014 12:30 PM, Tom Kerekes tk@... [DynoMotion] wrote:

Hi David,

In that case there should be very little power draw from the supply. Something improper must be going on. Could the system have homed improperly? Maybe driving continuously against the hard stop?

Did both failure happen in the same manner?

You might add a fuse. Maybe 20Amps.

Regards

TK