Danfoss Turbocor TT Series, Service Manual

Page: 142 / 294

Figure 4-141 SCR Connections - TTS/TGS/TTH/TGH Rev. F and Earlier (Except TTS300/TGS230)
Figure 4-142 SCR Connections - TTS/TGS/TTH/TGH Rev. H (Except TTS300/TGS230)
4.18.2 SCR Verification
NOTE
A faulty SCR module can cause the DC bus and Mains Input current to be imbalanced. This can stress the Inverter and Stator. If an SCR
module is found to be faulty, then the Inverter and Stator must also be verified.
4.18.2.1 Diodes Verification - Two-Hole Mount
1. Isolate compressor power as described in Section 1.8 Electrical Isolation on page 22.
2. Remove the DC Bus Bars from the SCRs. Refer to Section 4.21.3 DC Capacitor Bus Bar Assembly Removal
and Installation on page 168.
3. Using a multimeter set for diode measurements, place the black (-) lead on terminal 1 of the SCR and
place the red (+) lead on terminal 3. The measured value should be between 0.3V and 0.45V. Refer to
Figure 4-143 SCR Terminals - Two-Hole Mount on page 143 and Figure 4-144 SCR Terminals - Four-Hole
Mount on page 143 for terminal locations.
4. All other terminals should read infinity or open in both directions (polarity). Refer to Table 4-28 SCR
Diode Values on page 144.
5. Perform this test for each SCR.
Page 142 of 294 - M-SV-001-EN Rev. H 1/23/2023