2-14
Malfunctions with Indications
VP-10
(cont.)
Feedback Loss
(Selectable Soft
or Warning)
(Parameter 101
bit 0 when
Parameter
630=1)
This fault is disabled if under param 621 “Feedback
Device Type”, No Feedback Device is selected.
•
The following applies when VP-10 is configured
as a warning fault:
Tach loss can be configured as a warning fault if
parameter 691 “Tach Switch Sel” has been set to 1.
When this feature is enabled, a loss of feedback is
detected and the drive goes into Tach Loss
Recovery mode. Refer to 1395 Installation Manual.
The drive runs in Armature Voltage Feedback as
soon as a Warning is given; the process accuracy
may change.
8. Verify the armature resistance compensation. This value
effects the calculated CEMF of the motor. Parameter 614
should be programmed between 3-15% for typical motors.
9. Verify that the Field parameters are correctly setup
because this can also effect the accuracy of the armature
voltage generated. Reference the Start-up Procedure in
the Installation Manual for field parameter calibration.
10.Nuisance trips occur at random but no actual loss of
velocity feedback can be detected, re-evaluate the values
entered for parameters 731 “Tach Loss CEMF” and 732
“Tach Loss Vel”. Increase parameter 731 and decrease
732 by approximately 20% to decrease the overall
sensitivity of the feedback loss test. Execute a Clear Fault
and continue operation.
11.Verify encoder wiring (i.e. loose encoder case ground or
terminal strip ground).
12.An error in feedback can occur without a VP-10 fault.
Example: 106 indicates 75 RPM, but actual speed is 300
RPM. Verify correct value in 609, check encoder & wiring.
VP-12
Absolute
Overspeed (Soft)
(Parameter 101
bit 2 when
Parameter
630=1)
An Absolute Overspeed fault will occur when the
measured motor velocity, displayed in parameter
106 “Velocity Fdbk”, exceeds either parameter 607
“Rev Speed Limit” or parameter 608 “Fwd Speed
Limit” by the value specified in parameter 724 “ABS
Overspeed”. A coast stop will be initiated.
If Velocity Fdbk < Rev Speed Limit-ABS Overspeed
THEN Fault on VP-12 Absolute Overspeed OR IF
Velocity Fdbk > Fwd Speed Limit + ABS
Overspeed THEN Fault on VP-12 Absolute
Overspeed.
The Fwd and Rev Speed Limit parameters specify
the level at which all velocity commands will be
clamped. Parameter 608 “Fwd Speed Limit” sets
the forward direction speed clamp while parameter
607 “Rev Speed Limit” sets the reverse direction
clamp. Parameter 724 “ABS Overspeed” specifies
the incremental speed above the limits that is
allowable before an absolute overspeed fault
occurs. This value is the same for either forward or
reverse operation even though the speed limits
may be at different values. This fault is disabled if
the drive has armature voltage feedback or No
Feedback Device selected in parameter 621.
The method of recovery varies greatly depending on the
cause of the fault. The following may have contributed.
1. An overhauling load on the motor may have overcome the
torque output of the drive or motor and thus velocity
control was lost. Correct the situation and execute a Clear
Fault.
2. Check the absolute overspeed threshold level
programmed in 724 “ABS Overspeed”. Typical value is
10% of programmed speed limits to allow normal amounts
of velocity overshoot.
3. If parameter 625 “Torque Mode” is inadvertently
commanded to (2) External Torque Regulate, (3) Min
Select, or (4) Max Select mode while operating as a stand
alone or master drive of a system, velocity regulation
would be lost and the motor velocity may become
excessive causing this fault. Correct the mode command
and execute a Clear Fault to continue.
4. If the velocity loop is improperly tuned the velocity of the
motor may overshoot excessively during a step type
velocity reference change, causing this fault. Check the
gains of the velocity loop and execute a Clear Fault to
continue operation.
5. If nuisance trips occur at random, but no loss of velocity
control can be detected, the value of parameter 724 “ABS
Overspeed” may be too low. Decrease the sensitivity of
this test by increasing the value of parameter 724 by 10%.
Execute a Clear Fault to continue operation.
Velocity Processor Faults
No.
Name
Description
Recovery
!
ATTENTION:
Do Not execute a Clear Fault without correcting the cause of the fault. This will
allow the drive to operate and may cause undesirable operation. The hazard of personal injury
or equipment damage exists if faults are not corrected.
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