Rockwell Automation 21G PowerFlex 750-Series AC Drives Reference Manual - Manual (Page 21)

Rockwell Automation Publication 750-RM001F-EN-P - February 2012 21
Safety Concept Chapter 1
Output Pulse Test Considerations
If the pulse testing of
any safety output is disabled, the maximum safety rating
will be up to and including SIL CL2, PL d, and CAT 3 for any safety chain
incorporating
any input or output of the safety option.
You may need to disable pulse-testing if the connected device does not support
OSSD inputs. Refer to the product documentation for your connected device.
Encoder Considerations
When configured correctly, the safety option performs these diagnostics on the
encoder:
• Sin 2 + Cos 2 diagnostic
• Detection of open or short-circuit
• Encoder supply voltage monitoring
• Detection of illegal quadrature transitions of the sine and cosine signals
You can use motors that use a single-encoder application if they meet the
following criteria:
• Motor is a Permanent magnet (PM) brushless AC motor
• Motor controller utilizes the single encoder for control of IGBT firing
(commutation)
• Controller is not configured for auto transition to encoderless
commutation in the event of encoder failure
• Encoder is of the Sin / Cos type
• Motor / Encoder coupling is designed so as to exclude shaft slippage as a
failure mechanism (optional – such as tapered fittings)
IMPORTANT Setting any of the P72 [SS Out Mode], P73 [SLS Out Mode], or P74 [DC Out
Mode] parameters to 1 = No Pulse Test disables internal diagnostics as well as
external diagnostics required to achieve higher safety ratings.
You must exercise the SS_In input at least once every six months.