IGBT Power Source Trips and Shows Alarm of High Frequency and Over Current

Did you ensure that the shield integrity is continuous? If not, you can get capacitive Charging current spikes that look like an over current to whatever is monitoring it.

Thank you for the reply . The shield integrity is continuous, this is a water cooled co axial cable, at the jinction where the inner core strands are soldered, and in between outer core there exists a teflon bush of 1.0mm wall thickness and a gap of 2mm exists between OD of inner core and bore of outer core bush, in between this gap is the teflon bush, the strands used are 2sq,mm x 18 nos ( 37 strands of 0.25 mm dia ) teflon coated ,just as original ,

these are not tightly packed inside the tube carrying DM water , thus during movement chances of central conductors moving inside the external conductors may arise. does this change the cable characteristics?

"Movement of central conductor" inside the external conductors, may create an unwanted changes in its characteristic impedance! Any movement changes the separation space separating the two conductors. This physical changes in space or gaps may introduce a corresponding net changes in the cable impedance as a result of its varying capacitance between the internal and external electrodes....

Dear Sir,

thank you for the reply, Please elaborate over high frequency alarm, what would be the

possible causes. does poor insulation strength of base plate where transformer's secondary is connected through adaptors on a single base plate , give rise to such high frequency alarm in which case secondary of transformer is getting partially shorted?

I have no confident about that and I would no further advice you what to do.

If you are in-charge on this, in the first place, you should be will equipped with the technology and science behind it.

If it's not probably a supply quality problem, the issue may involve above (series or parallel RLC circuitry analogy)

I advice you hire or consult an expert on this issue.

COAX cable is available in different impedance values and are specific to the application.

In sensitive applications the overall length of the COAX cable can affect the controls.

If the issues were not present before you changed the COAX cable it may be that you have installed the wrong cable and/or the new cable or connector(s) are bad.

The length and outside diameter of the center core COAX conductor are critical.

If the center conductor is too small or does penetrate the connector far enough intermittent signal issues will occur and can cause control issues as you have described.

Also; If the machine was in operation when the COAX was damaged it could well be that internal damage has occurred to the IGBT control(s).

I suggest an in-depth examination of the COAX cable first including finite measurement of the center conductor outside diameter with a micrometer and verification that the length meets factory requirements.

I would also suggest you obtain the factory specifications on the COAX cable then buy or rent a cable tester to test the new cable(s) for compliance.

If the cable passes examination then an in-depth control analysis is in order.

You first mentioned

Power Source Trips and Shows Alarm of High Frequency and Over Current.

Then you mention over voltage, and or high current. Please clarify these alarms, and if they are all secondary, or if any are primary. While your focus is on the new cable, what damage was done to the old cable? Was it shorted, or open? Even if the IGBT's seem good, there could be some damage to them, or the circuitry associated with them. Check Gate Drive circuitry, look for any burned resistors or damaged parts. RAMConsult gave you good advise regarding the cable. Have you asked the Manufacturer about the cable, and or problems experienced?