Siemens Sinamics repair, faulty motor phase 6SL3120-1TE23-0AA3

Siemens Sinamics repair, faulty motor phase 6SL3120-1TE23-0AA3
Device	Sinamics 6SL3120-1TE23-0AA3
Affects part(s)	IGBT module
Needs equipment	Screwdriver set, soldering iron, soldering station, multimeter
Difficulty	◉◉◉◌ Hard
Type	Soldering, Part replacement

Problem description

Diagnosing and fixing a problem with a Siemens inverter Sinamics 6SL3120-1TE23-0AA3 that has a faulty output phase

Healthy phase measurement, (negative on + DC link and vice versa to all phases should read this value) Figure 1

Dead phase measurement (figure 2)

The IGBT model for this inverter (figure 3)

Symptoms

• Open line or short circuit from DC link to one or more of the output phases.
• Unstable operation of the motor, spins little bit and stops.

Solution

Diagnostic Steps

• First, check the IGBT

• Place your red probe on - DC link, and the black all the phases individually, they should measure close to the value on figure 1
• Do the same with black probe on + DC link
• If you measure all the values to be the same, then you have another issue, the IGBT is healthy
• If you measure OL or low/short on one of the phases, proceed to repair steps
  

Repair Steps

Replace the IGBT (Figure 3) and make sure the driving circuit isn't damaged, if you have a healthy phase you can compare since they're identical, measure the optocouplers/diodes.

After replacement the inverter should work properly.