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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.
9.1 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 Parameter:
16-12 Battery Clock
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 Parameters: 2-3 - 2-3 and 16-2
Excess Start Time
Excess start time trip can occur in the following conditions:
•
1-1 Motor Full Load Current
is not appropriate for the motor
•
1-4 Current Limit
•
1-6 Start Ramp Time
has been set greater than the setting for
1-9 Excess Start Time Setting
•
1-6 Start Ramp Time
is set too short for a high inertia load when using Adaptive Acceleration
Control
Related Parameters: 1-1, 1-6, 1-4, 1-9, 7-9, 7-1, 7-6, 7-4, and 16-7
FLC Too High
The MCD 500 can support higher motor FLC values when connected to the motor using inside
delta configuration rather than in-line connection. If the soft starter is connected in-line but the
programmed setting for
1-1 Motor Full Load Current
is above the in-line maximum, the soft starter
will trip at start.
Related Parameters:
1-1 Motor FLC
,
7-1 Motor FLC-2
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 Parameters: 2-8, 2-9, 2-10, and 16-5
Troubleshooting
MCD 500 Operating Instruction
70
MG17K402 - VLT
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is a registered Danfoss trademark
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