Allen-Bradley 1395, Руководство по устранению неисправностей

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3-14 Malfunctions Not Indicated by a Fault
4. This input voltage at base speed is then converted to raw Adapter units
according to the equation given here.
5. The Raw Adapter units are then used to determine the correct scaling
parameter value according to the equation shown here
6. The scaling parameter value should then be entered into the associated
analog input scaling set-up parameter. This procedure should be correct
to within 5%. Verify that the scaling is correct by measuring the actual
motor velocity with a hand tachometer. Fine tune the scaling by
adjusting the appropriate value to minimize any error.
7. Any drift at zero speed can be virtually eliminated by adjusting the offset
parameter associated with the channel in use.
Below is a list of malfunctions, symptoms, and possible solutions.
Base Speed Input x 2048
10
= Raw Adapter Units
4096
Raw Adapter Units
= Scaling Parameter Value
Analog Tachometer Malfunctions
Malfunction Symptom Solution
Drive faults on “VP-10
Feedback Loss”. This indicates
that the measured velocity from
the tachometer is less than the
level programmed in parameter
732 “Tach Loss Vel” and the
velocity calculated from the
CEMF of the motor is greater
than the level programmed in
parameter 731 “Tach Loss
CEMF”. The velocity feedback is not being
registered in parameter 156. Rotate the
shaft of the motor, either by mechanical
means or under armature voltage
feedback control.
Note: If using armature voltage feedback
to troubleshoot the tach circuit, the
set-up procedure for armature voltage
feedback must be performed first for
proper operation.
If the Adapter configuration parameter
indicates proper data, an incorrect
configuration link is in the drive.
Verify that the analog input configuration parameter is linked to
parameter 154. Also verify that external velocity feedback is
selected. Examine parameter 621 “Fdbk Device Sel” to verify its
value is 2.
Adapter configuration parameter
indicates no velocity feedback. Tach
signal incorrectly connected to 1395. Verify that the tach signal is present at the TB3 terminals which
correspond to the desired analog input channel. If it is not, then
check all wiring and connections that exist between the 1395 and
the tachometer. If the wiring is functional replace the tachometer.
If the signal is present at TB3, verify the scaling and offset
parameters associated with the selected analog input channel.
Velocity control is maintained
until the velocity exceeds a
certain threshold and the motor
accelerates uncontrollably. The velocity feedback is proportional to
the velocity of the motor until a certain
level is reached and the velocity
feedback value is clamped and the
motor accelerates uncontrollably. The tachometer voltage is exceeding the input voltage range of
the analog input channel on the adapter board. When the voltage
range is exceeded the feedback data will become clamped and
the motor will accelerate uncontrollably. It will be necessary to
rescale the voltage divider network, external to the drive, to
assure that the tach signal will remain inside the operating range
of the analog input channel throughout the entire speed range of
the motor.
The motor is rotating at the
wrong speed. The velocity feedback viewed in
parameter 106 “Velocity Fdbk” does not
match the actual velocity of the motor, as
measured by independent means (hand
tach). The scaling of the tach signal must be verified. The first scaling
takes place at the voltage divider network which reduces the tach
output to a level within the 10V input range. The second scaling
takes place in the adapter board which converts the incoming
signal to Drive Units representing motor velocity.
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