9 Troubleshooting
When a protection condition is detected, the MCD 500 will write this to the event log and may also trip or issue a warning. The soft starter's response to
some protections may depend on the Protection Action settings (parameter group 16).
If the MCD 500 trips you will need to reset the soft starter before restarting. If the MCD 500 has issued a warning, the soft starter will reset itself once
the cause of the warning has been resolved.
Some protections cause a fatal trip. This response is pre-defined and cannot be overridden. These protection mechanisms are designed to protect the
soft starter, or can be caused by a fault within the soft starter.
9.2 Trip Messages
This table lists soft starter's protection mechanisms and the probable cause of the trip. Some of these can be adjusted using parameter group 2
Protection
and parameter group 16
Protection Action
, other settings are built-in system protections and cannot be set or adjusted.
Display
Possible cause/Suggested solution
Battery/Clock
A verification error has occurred on the real time clock, or the backup battery voltage is low. If the battery
is low and the power is off, date/time settings will be lost. Reprogram the date and time.
Related Pars.: 16-12
Current Imbalance
Current imbalance can be caused by problems with the motor, the environment or the installation, such
as:
-
An imbalance in the incoming mains voltage
-
A problem with the motor windings
-
A light load on the motor
Current imbalance can also be caused by incorrect cabling between the external bypass contactor and the
soft starter or an internal problem with the soft starter, particularly an SCR that has failed open circuit. A
failed SCR can only be definitely diagnosed by replacing the SCR and checking the starter's performance.
Related Pars.: 2-2, 2-3, 16-2
Excess Start Time
Excess start time trip can occur in the following conditions:
-
The FLC setting is wrong
-
The Current Limit has been set too low
-
The Start Ramp Time has been set greater than the Excess Start Time setting
The Start Ramp Time is set too short for a high inertia load when using adaptive acceleration control
Related Pars.: 1-1, 1-6, 1-4, 1-9, 7-9, 7-1, 7-6, 7-4, 16-7
FLC Too High
The MCD 500 can support higher motor FLC values when connected to the motor using inside delta con-
figuration rather than in-line connection. If the soft starter is connected in-line but the selected motor FLC
is above the in-line maximum, the soft starter will trip at start.
Related Pars.: 1-1, 7-1
Frequency
The mains frequency has gone beyond the specified range.
Check for other equipment in the area that could be affecting the mains supply (particularly variable speed
drives).
If the MCD 500 is connected to a generator set supply, the generator may be too small or could have a
speed regulation problem.
Related Pars.: 2-8, 2-9, 2-10, 16-5
MCD 500 Operating Instruction
9 Troubleshooting
MG.17.K2.02 - VLT
®
is a registered Danfoss trademark
83
9
