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APPENDIX
– Safe-Off
160
The safe off feature is enabled by setting the switch in the center of the control card from I9 (Input 9) to
BE (Base Enable) as per figure 1. This allows the IGBTs to be enabled when logic input 9 is closed
(Logic high), and disabled when logic input 9 is open (Logic low).
Figure 1.
Switch set to BE on the left (Safe off on) or I9 on the right (Safe off disabled)
Switch
With the switch set to the left
at the “BE” position, the drive will only be able to fire the IGBTs when an
input on logic input 9 is high. The car controller will need to supply this feed in the same way that they
would usually supply the signal for the contactors to close, the drive will require the usual 24V feed as
in the case of the rest of the logic inputs. This input must be fed from a pilot relay switched by the
controller.
Input
Regardless of the setting of logic input 9 in the C2 menu of the drive, the IGBTs will not fire unless this
feed is present on terminal TB1-
26 (Logic Input 9). Although the “Safe Off” function is a purely
hardware feature, the drive’s software will still monitor the status of logic input 9, and has been
designed to give intuitive feedback based on the state of this input. With that in mind, for correct
operation the logic input 9 in C2 should be set to “SAFE-OFF”. The drive can then give diagnostic
information if and when the IGBTs are shut off (in the event of a crash stop for example), much in the
same way that it would declare a contactor fault if contactor monitoring were enabled.
Output
One of the drive’s logic outputs can be set to “SAFE OFF INPT”. The car controller should monitor the
state of this output, much in the same way that motor contactors would be monitored. The car
controller can also use the status of this output to verify that the “Safe Off” function has been set up
correctly, i.e. the logic output matches the status that the controller would expect from a contactor
auxiliary. The controller can therefore determine if the installation has been set up in an unsafe
manner if only one contactor is used, but the drive’s “Safe-Off” function is not implemented correctly.
Th
is output will be HIGH when the drive’s internal Safe Off circuitry is active (IGBTs are disabled and
torque CANNOT be produced in the motor). The output will be LOW when the drive’s internal Safe Off
is inactive (IGBTs are enabled, and torque CAN be produced in the motor).
Parameter Settings
The parameters for the “Safe Off” function should be configured as follows:
Parameter Name
Setting
Function
Logic Input 9 (C2)
SAFE-OFF
Only Logic Input 9 can be used for the “Safe Off” input. This
parameter monitors the status of the input and allows the
drive to declare diagnostic information in the event of the
input not matching the expected status during each drive
state (Ready and Run).
Logic Output 4* (C3)
SAFE-OFF INPT
Provides feedback to the car controller of the status of the
Safe Off Input, and therefore the status of the IGBTs