Chapter 7 – Trouble Shooting & Maintenance
7-5
Protective
Function
Cause Remedy
NTC Open Internal thermistor has failed open or is disconnected.
125 HP and below, thermistor is
internal to IGBT block. Repair is
required.
150 HP and above, thermistor is heat
sink mounted. Connection is at Main
SMPS bd., connector CN7.
Ext. OHT External Thermistor has reached trip temperature.
Verify motor heating.
Check programming of I/O-97 and
I/O-98.
Fan Lock
(150 HP and above)
1) Possible fan board failure.
2) Each Fan Bd. Monitors the connected fans internal thermal
switch to detect a fan failure.
1) Verify power LED is on for each
fan bd.
2) Pins 1 & 2 of connectors CN3 and
CN4 on the Fan bd.
Fuse Open
(40 HP and above)
1) Internal fuse detector has detected a blown DC Bus Fuse. On
500 HP ~ 700 HP, these are line (input) fuses.
1) Check Fuses.
2) Determine cause of high current.
No Motor Trip
1) The drive has detected no current flow out of the drive.
2) The drive has detected a low current level condition.
1) No motor connection
2) Low level of current set by
parameters FUN-57, 58 and 59.
Disabled with parameter FUN-57 set
to “No”.
Frequency (Speed)
Reference is Lost
Loss of Frequency Reference from:
LOV - V1 input
LOI - I input
LOA - Pulsed input
LOR - Remote Communications
Eliminate cause of fault.
Over Lap
(flashing)
Displayed when more than one digital input terminal (M1 – M8)
is programmed to the same function.
Check parameters I/O-20 ~ I/O-27 for
duplication.
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