Ohm Checking the Simodrive Power Section
Caution!  It must be assured that power is removed and the DC Bus has drained to a safe level before any connections are removed or checked!

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After you are sure that the DC Bus has safely discharged , a DVM on the Diode scale can be used to detect if a  short circuit or open exists in the power section.  Readings will vary with module size.

Note:   P600 and M600 are the 600 V DC Bus connections.  U2, V2 and W2 are the motor connections.

• Disconnect the P600, M600 bus bars, U2, V2 and W2 connections.  This isolates the power module from the motor and DC Bus.
• Diode check between P600 and U2, then V2 then W2. There should be continuity with the – lead on P600 and the + lead on U2, V2 or W2.  Readings should be open with the leads reversed.
• Diode check between M600 and U2, V2, W2.  There should be continuity with the + lead on M600 and the – lead on U2, V2 or W2.  Readings should be open with the leads reversed.
• Diode check between P600 and M600.  There should be continuity with the + lead on the M600 and the – lead on P600.  The reading should be open with the leads reversed.
• Diode check between U2, V2 and W2.  All combinations should read open.

Note:  If all readings are open the internal DC Bus fuse is open.  If there is a 0Ω reading, there is a  short in the power circuit.
Note 2: Because of the capacitance in the power circuit, resistance checks will indicate a charging effect.  It is necessary to wait until the measurement has stabilized to determine if it is correct.  If possible, it is best to use a DVM with a diode check.

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