Thicknesser electrical problem, help needed!!

[Duffman]

Hi everyone, long time reader first time poster. I have a Tecnomax FS30 elite planner/thicknesser that is giving me a problem. When I turn the machine on it will run for about 20 seconds and then turn off, it is like someone pulled out the plug. The block will stop spinning within 10 seconds, if I turn it back on it will run for about 20 seconds again and then stop. It is a three phase machine and I have a 11kw/15hp digital frequency converter providing power to the workshop. Link to the converter here Digital Phase Converter 11Kw/15Hp 240V in 400V Out - JFK Electrical. This converter runs a dust extractor, panel saw, bandsaw and a morticer with no problem. Mind you not all at the same time. I only run the extractor and one of the machines at a time. I have run the thicknesser for a few hours in the past with no problem so this issue has just started to happen. I have attached the wiring diagram for the machine as well. Another piece of info that may help is that the fuse at FU 1 keep blowing and I don’t what what is causing it.
Any help anyone could give would be greatly appreciated.

 

[Spectric]

My initial thoughts would be the thermal trip in the DOL, as you say the other three phase equipment is working ok from the convertor.

That fuse FU 1 is supplying a transformer, this means your control side is at a lower voltage which could be 24 volts Ac and if this fuse keeps blowing then check the fuse rating and type is correct. If this is ok then investigate the transformer and wiring on the primary side, any smells or discolorisation.

 

[Duffman]

My initial thoughts would be the thermal trip in the DOL, as you say the other three phase equipment is working ok from the convertor.

That fuse FU 1 is supplying a transformer, this means your control side is at a lower voltage which could be 24 volts Ac and if this fuse keeps blowing then check the fuse rating and type is correct. If this is ok then investigate the transformer and wiring on the primary side, any smells or discolorisation.

Hi Spectric, thanks for coming back to me. Pardon my ignorance but what is a DOL? You can see the transformer in the third picture with the orange blocks on either side of it. It is putting out 110v to the control side. The funny thing is even with the fuse at FU1 blown the machine still starts and all the control switches still work. I just got a box of 10x38 1A 500v fuses. I think these are the correct rating and are the exact same as what was in the machine. As far as I can tell there is no burning smells and I can’t see any discolouration On any wires. How would I test the transformer.

 

[Spectric]

Pardon my ignorance but what is a DOL

It is a direct on line starter, a set of contacts that are pulled in by a coil. The start button energises the coil and it latches via the stop button which is a set of normally closed contacts. When the stop button is operated it breaks the coil circuit and the contacts drop out.

Within this device is a thermal cut out which is there to provide overload protection, if too much current flows in the phase wires they heat up and open the circuit to protect the motor and wiring.

To test the transformer you would need an insulation tester which would measure the impedance of the primary windings at a set voltage.

The fact that the machine still functions with the fuse blown indicates something is wrong, that transformer takes two of the phases (400 volts) on the primary to produce 110 volts on the secondary. If it still works with the fuse blown then there should be no current flowing in the primary windings, no magnetic flux and therefore no current induced into the secondary windings so nothing to operate the control circuitry. If it is working then that suggest there is a path from the single 400 volt line via the windings to ground so current will flow, but the other line where the fuse blows sees a short, impedance too low as it is close to the point where the short to ground is located.

To prove this synario remove the fuse FU 1 and see if it works, if it does then remove the earth wire connected to the transformer laminations and now see if it still works. If it no longer works then there is a leakage path within the transformer.

When under taking this test DO NOT TOUCH any conductive part of the system in case there is a voltage present due to that earth wire being removed.

 

[MikeK]

To add what @Spectric (Roy) wrote, you have a the SCM FS30 Elite sold under the Tecnomax name. The FS30 series machines are also sold under the Holzkraft and Minimax names, but they are all the same machine. The FS30 is a great P/T and I have a version of it.

The magnetic overload (FS in the electrical schematic) is the rotating switch on the panel, which also incorporates the Start/Stop switch (SB1 in the electrical schematic). An overload on any of the three phases will cause the FS to open and stop the P/T.

The fuses FU1, FU2, and FU3 are all related to the transformer (TC in the electrical schematic). I don't know why SCM decided to make the control voltage in this machine 110V, but both of my 3-phase SCM machines, and others I have worked on, use 400V for the control circuits. This must be a feature specific to the Tecnomax branding, as I have never seen it in any other SCM machine.

If any of these fuses are open, then the P/T cannot start because the coil to the contactor (KM in the electrical schematic) cannot energize. If any of these fuses are open and the P/T starts, then there is a serious problem with one or more of the components and/or wiring.

 

[Spectric]

I don't know why SCM decided to make the control voltage in this machine 110V, but both of my 3-phase SCM machines, and others I have worked on, use 400V for the control circuits.

Hi Mike

I believe basing this on the UK that if the controls are contained within the starter or DOL then having a 400 volt coil is ok, but once you have remote control stations for a motor / machine where the wiring runs externally to control panels then it is deemed safer to use a lower voltage as the risk is perceived as lower. They used 110 volts but at some point realised that this is only marginally safer than 230 volts and a lot of the control circuits became 24 volt Dc.

 

[Duffman]

It is a direct on line starter, a set of contacts that are pulled in by a coil. The start button energises the coil and it latches via the stop button which is a set of normally closed contacts. When the stop button is operated it breaks the coil circuit and the contacts drop out.

Within this device is a thermal cut out which is there to provide overload protection, if too much current flows in the phase wires they heat up and open the circuit to protect the motor and wiring.

To test the transformer you would need an insulation tester which would measure the impedance of the primary windings at a set voltage.

The fact that the machine still functions with the fuse blown indicates something is wrong, that transformer takes two of the phases (400 volts) on the primary to produce 110 volts on the secondary. If it still works with the fuse blown then there should be no current flowing in the primary windings, no magnetic flux and therefore no current induced into the secondary windings so nothing to operate the control circuitry. If it is working then that suggest there is a path from the single 400 volt line via the windings to ground so current will flow, but the other line where the fuse blows sees a short, impedance too low as it is close to the point where the short to ground is located.

To prove this synario remove the fuse FU 1 and see if it works, if it does then remove the earth wire connected to the transformer laminations and now see if it still works. If it no longer works then there is a leakage path within the transformer.

When under taking this test DO NOT TOUCH any conductive part of the system in case there is a voltage present due to that earth wire being removed.

Roy, I have to say it never ceases to amaze me the level of knowledge people have on this forum. This is probably the best answer I have ever received to a question I asked. Thanks for the detailed explanation of what a DOL is, every day is a learning day. I had the fuse at FU1 out of the machine altogether and the machine ran for 20 seconds and then cut out. I will removed the earth wire from the transformer and turn the machine on with a stick taking care not to touch any metal parts on the machine. If the machine does not start at all does this mean that the problem is in the transformer?

 

[MikeK]

Hi Mike

I believe basing this on the UK that if the controls are contained within the starter or DOL then having a 400 volt coil is ok, but once you have remote control stations for a motor / machine where the wiring runs externally to control panels then it is deemed safer to use a lower voltage as the risk is perceived as lower. They used 110 volts but at some point realised that this is only marginally safer than 230 volts and a lot of the control circuits became 24 volt Dc.

Roy,

It must be a UK thing for this machine. My saw and P/T have a separate starter and DOL and the coils are 400V.

 

[Duffman]

To add what @Spectric (Roy) wrote, you have a the SCM FS30 Elite sold under the Tecnomax name. The FS30 series machines are also sold under the Holzkraft and Minimax names, but they are all the same machine. The FS30 is a great P/T and I have a version of it.

The magnetic overload (FS in the electrical schematic) is the rotating switch on the panel, which also incorporates the Start/Stop switch (SB1 in the electrical schematic). An overload on any of the three phases will cause the FS to open and stop the P/T.

The fuses FU1, FU2, and FU3 are all related to the transformer (TC in the electrical schematic). I don't know why SCM decided to make the control voltage in this machine 110V, but both of my 3-phase SCM machines, and others I have worked on, use 400V for the control circuits. This must be a feature specific to the Tecnomax branding, as I have never seen it in any other SCM machine.

If any of these fuses are open, then the P/T cannot start because the coil to the contactor (KM in the electrical schematic) cannot energize. If any of these fuses are open and the P/T starts, then there is a serious problem with one or more of the components and/or wiring.

Hi Mike, again thanks for all the info, it’s great to be able to talk with people who know this stuff inside out. You are right it is a great machine, it will be better when I get this problem sorted. As for the fuses when the fuse at FU1 blew I completely removed the fuse from the machine and the machine would still start run for about 20 seconds and then stop, so as you said I think we have a serious problem. I think Roy maybe on to something with the earth wire on the transformer. I am going to remove it and try and turn on the machine. If it does not start we will know there is a problem with the transformer.

 

[Spectric]

Probably correct in that the Uk does seem to do things that once in place don't get changed and just become accepted. Mike, you say they have a separate starter but is it attached to the machine ? Another case where lower voltage control circuits are used is when remote E-STOPs are used. Moving away from only machines to larger industrial applications then you see mostly lower voltage control circuits and they become essential once you get into safe systems with SIL ratings because protection relays such as ones from pilz are 230 Vac or 24 Vdc and keeping everything at 24 volts makes design easier because it opens up a wider range of sensors.

 

[MikeK]

Roy, I'm likely confusing the issue by not using UK terms. In my machines, the thermal overload is the rotary switch on the front panel. The switch also has an auxiliary contact that is the Start/Stop switch to energize the DIN-rail mounted contactor. Every component is in the machine, and with the exception of the limit switch and emergency stop switch, the components are in the closed electrical bay behind the rotary switch panel. The voltage for the control circuits, including the limit and emergency stop switches, is 400V. All wiring is within the machine chassis and not accessible without removing panels. On my former 230V Holzmann P/T, the control circuit for the two limit switches, emergency stop switch, and start/stop buttons was 230V.

I don't like this configuration on the saw, because the rotary switch is in an uncomfortable position. Now that the warranty has expired, I will replace the components with a DIN-rail mounted contactor, with integrated thermal overload, and at least two sets of remote start/stop buttons so I can control the saw without bending over and around the sliding sled.

 

[Duffman]

Hi @MikeK and @Spectric i woke up this morning with great excitement to try out the advice you gave for my electrical problem with the thicknesser. I made 2 videos, video 1 Thicknesser - Google Drive shows the P/T being started with the fuse at FU1 totally removed from the machine and it runs. Video 2 Thicknesser - Google Drive shows that the fuse at FU1 is totally removed and the earth cable to the transformer has been removed and the machine still starts. This is turning out to be a right head scratcher!! What is next on the list to try?

 

[MikeK]

I can't view your movies on Google Drive because the software prompts me to download an app, which I won't do. I'll take your word that the motor starts.

The next troubleshooting option I recommend is to completely isolate the output of the transformer by removing the two red wires identified by the white arrows in the photo below. You can tape up the ends to prevent them from shorting out to the chassis.

This effectively removes the 110V control voltage from the system. If the motor starts after doing this, then you have a serious problem with the machine.

 

[Spectric]

So we know that only one side of the primary of the transformer is connected to the 400 volt line, the other is open circuit with the fuse removed but there is a current flowing otherwise you would have no output on the secondary side, the question is what is making up the primary flow path. If it is flowing to ground then you will only have a 230 volt supply and the secondary output will be lower than 110 volts, can you measure the output from the transformer to see if it is 110 volts or what ?

That enclosure, is it ABS / Polycarb or diecast ? The reason I ask is that if it is a non conductive material then it rules out certain paths, if conductive then it will be grounded to earth and so offers other potential flow paths.

I don't like this configuration on the saw, because the rotary switch is in an uncomfortable position. Now that the warranty has expired, I will replace the components with a DIN-rail mounted contactor, with integrated thermal overload, and at least two sets of remote start/stop buttons so I can control the saw without bending over and around the sliding sled.

I don't know what regulations you have in Germany but in the UK we have PUWER ( Provision and Use of Work Equipment Regulations 1998 ) but only applies in commercial settings and not home workshops. It would support the changes you are doing because it is essential to be able to operate any machinery without the operator placing themselves at any risk and is why I dislike the cheap On/Off buttons found on so many woodworking machines because it is not as easy to fit more accessable controls like you can with an industrial quality DOL.

 

[Spectric]

If the motor starts after doing this, then you have a serious problem with the machine.

I would say a miracle more than a problem !

 

[Duffman]

I can't view your movies on Google Drive because the software prompts me to download an app, which I won't do. I'll take your word that the motor starts.

The next troubleshooting option I recommend is to completely isolate the output of the transformer by removing the two red wires identified by the white arrows in the photo below. You can tape up the ends to prevent them from shorting out to the chassis.

This effectively removes the 110V control voltage from the system. If the motor starts after doing this, then you have a serious problem with the machine.

View attachment 153669

Hi Mike, I removed the two red cables from the transformer. The earth wire was also removed for the transformer as well at this time. The machine did not start and no power flowed in the control wiring this can be seen as there was no light in the switch at the front of the machine.

 

[Duffman]

So we know that only one side of the primary of the transformer is connected to the 400 volt line, the other is open circuit with the fuse removed but there is a current flowing otherwise you would have no output on the secondary side, the question is what is making up the primary flow path. If it is flowing to ground then you will only have a 230 volt supply and the secondary output will be lower than 110 volts, can you measure the output from the transformer to see if it is 110 volts or what ?

That enclosure, is it ABS / Polycarb or diecast ? The reason I ask is that if it is a non conductive material then it rules out certain paths, if conductive then it will be grounded to earth and so offers other potential flow paths.


I don't know what regulations you have in Germany but in the UK we have PUWER ( Provision and Use of Work Equipment Regulations 1998 ) but only applies in commercial settings and not home workshops. It would support the changes you are doing because it is essential to be able to operate any machinery without the operator placing themselves at any risk and is why I dislike the cheap On/Off buttons found on so many woodworking machines because it is not as easy to fit more accessable controls like you can with an industrial quality DOL.

Hi Roy, all sides of the enclosure where the electrics are enclosed are metal you you can see from the photos that a magnet sticks to all surfaces.
I have also added a pic of the multimeter I have. I am a pure novice using it. Can you tell me what you want me to test on the transformer and what setting to have the multimeter at. Thanks again.

 

[Spectric]

What voltage is present on the secondary output ? Then can you reconnect those two red wires but leave out that earth ? Hopefully it will still not run !!!! That earth could be the path for a short in the primary but ?

 

[Spectric]

Can you tell me what you want me to test on the transformer and what setting to have the multimeter at. Thanks again.

For testing these voltages you want the meter on the blue V with the wiggle above it which indicates Ac voltage and on 600. The black V opposite is for Dc voltage.

Next test is to reconnect those two red wires but leave out that earth ? This will prove if this is a current path for the primary.

 

[Duffman]

What voltage is present on the secondary output ? Then can you reconnect those two red wires but leave out that earth ? Hopefully it will still not run !!!! That earth could be the path for a short in the primary but ?

Hi Roy, I am not sure what you mean by “what voltage is preset on the secondary output?” The transformer is set to put out 110v. I reconnected the two red wires on the secondary side of the transformer, leaving out the earth wire from this connection. That means that both earth wires on the transformer are not connected. When I put power to the machine the light on the on switch on the front of the machine lights up, so there is power running through the control circuit. But when I press the on switch the machine does not start. Hopefully we are getting somewhere.