Rockwell Automation FlexPak 3000 Digital DC Drive Version 4.3 - Manual (Page 144)

13-12 FlexPak 3000 DC Drive Software Reference
13.2 Adjusting the Tachometer or Encoder
Loss Sensitivity
Normally, tachometer or encoder loss is reported when the SCR firing angle reaches
109° when armature current is present and the speed feedback is less than 5% of TOP
SPEED (P.011). If you are getting nuisance trips associated with high inertia loads, you
can adjust the SCR angle at which tachometer or encoder loss is reported.
If you are getting nuisance tachometer or encoder loss trips:
Step 1. Lockout and tag power as necessary.
Step 2. Turn off power to the drive.
Step 3. Check all tachometer or encoder lead connections, including polarity.
Step 4. If there is no problem with the connections, increase TACH LOSS SCR ANGLE
by 1 degree.
Step 5. Restart the drive.
Step 6. If a tachometer or encoder loss is reported and the angle is less than 127°,
repeat this procedure.
!
ATTENTION: This equipment is at line voltage when AC power is
connected to the drive. Disconnect and lock out incoming power to the
drive before proceeding. After power is removed, verify that no voltage
exists at power terminals 181, 182, and 183 before touching any internal
parts of the drive. Failure to observe this precaution could result in severe
bodily injury or loss of life.
TACH LOSS SCR ANGLE (P.608)
The SCR firing angle
at which tachometer
or encoder loss is
determined when
current is present and
motor speed is less
than 5% of
TOP SPEED
(P.011).
Parameter Range: 0 to 127 DEGREE
Default Setting: 109 DEGREE
Parameter Type: Tunable
OIM Menu Path(s): Additional Parameters (listed by parameter number)
This parameter is also used to determine an open armature. An open armature is
detected when the:
• armature current is zero
• motor speed feedback is less than 5% of TOP SPEED (P.011)
•
SCR firing angle is equal to TACH LOSS SCR ANGLE
!
ATTENTION: The incorrect setting of this parameter can cause an
overspeed condition. Set the value of this parameter only as high as
necessary to stop tachometer or encoder loss. Failure to observe this
precaution could result in bodily injury.