Rockwell Automation 7000L PowerFlex Medium Voltage AC Drive (C Frame) - Classic Control - Manual (Page 241)

4-36 Commissioning
7000L-UM300I-EN-P – June 2013 7000 “C” Frame
SCR Resistance Measurement Measured Resistance
SCR Anode-Cathode Resistance
(Chill block to Chill block)
__________ – __________ kΩ
(Lowest) (Highest)
SCR Gate-Cathode Resistance
(Across SCR Phoenix Connector)
__________ – __________ Ω
(Lowest) (Highest)
Snubber Resistance
(Test Point – Chill block on Left)
__________ – __________ Ω
(Lowest) (Highest)
Snubber Capacitance
(Test Point – White Wire from Snubber
Phoenix connector on Right)
__________ – __________ µF
(Lowest) (Highest)
Sharing Resistance
(Red Wire from Snubber Phoenix
connector – Chill block on Left)
__________ – __________ kΩ
(Lowest) (Highest)
SCR Anode to Cathode Resistance
Performing an Anode to Cathode resistance test verifies the integrity
of the SCR. Unlike the SGCT, the SCR uses the snubber circuit to
power the self-powered gate driver boards. The resistance measure-
ment taken across each SCR should be consistent; an inconsistent
value may indicate a damaged sharing resistor, self-powered gate
driver board or SCR.
Using an ohmmeter, measure the anode to cathode resistance across
each SCR in the rectifier bridge, while looking for similar resistance
values across each device. Easy access from the anode to cathode is
available by going from chill block to chill block as shown in the
diagram below:
Anode Chill Block Cathode Chill Block
SCR
Figure 4.8 – Anode to Cathode Test