8.2.1 Current Imbalance
If the currents on the 3 phases vary by more than a
specified amount, the soft starter can be configured to trip.
The imbalance is calculated as the difference between the
highest and lowest currents on all 3 phases, as a
percentage of the highest current.
Current imbalance detection is desensitized by 50% during
starting and soft stopping.
2-2 Current Imbalance
Range:
Function:
30%
*
[10–50%] Sets the trip point for current imbalance
protection.
2-3 Current Imbalance Delay
Range:
Function:
3 s
*
[0:00–4:00
(min:s)]
Slows the response of the soft starter to
current imbalance, avoiding trips due to
momentary fluctuations.
8.2.2 Undercurrent
If the average current of all 3 phases drops below a
specified level while the motor is running, the soft starter
can be configured to trip.
2-4 Undercurrent
Range:
Function:
20%
*
[0–
100%]
Sets the trip point for undercurrent protection,
as a percentage of motor full load current. Set to
a level between the normal motor working
range and the motor magnetizing (no load)
current (typically 25–35% of full load current). A
setting of 0% disables undercurrent protection.
2-5 Undercurrent Delay
Range:
Function:
5 s
*
[0:00–4:00
(min:s)]
Slows the response of the soft starter to
undercurrent, avoiding trips due to
momentary fluctuations.
8.2.3 Instantaneous Overcurrent
If the average current of all 3 phases exceeds a specified
level while the motor is running, the soft starter can be
configured to trip.
2-6 Instantaneous Overcurrent
Range:
Function:
400%
*
[80–600%
FLC]
Sets the trip point for instantaneous
overcurrent protection, as a percentage
of motor full load current.
2-7 Instantaneous Overcurrent Delay
Range:
Function:
0 s
*
[0:00–1:00
(min:s)]
Slows the response of the soft starter to
overcurrent, avoiding trips due to
momentary overcurrent events.
8.2.4 Frequency Trip
The soft starter monitors mains frequency throughout
operation and can be configured to trip if the frequency
varies beyond a specified tolerance.
2-8 Frequency Check
Option:
Function:
Determines when the soft starter monitors for a
frequency trip.
Do not check
Start only
Start/run*
Run only
2-9 Frequency Variation
Option: Function:
Selects the soft starter tolerance for frequency
variation.
±
2 Hz
±
5 Hz*
±
10 Hz
±
15 Hz
2-10 Frequency Delay
Range:
Function:
1 s
*
[0:01–4:00
(min:s)]
Slows the response of the soft starter to
frequency disturbances, avoiding trips due to
momentary fluctuations.
NOTICE
If the mains frequency drops below
35 Hz or rises above 75 Hz, the soft
starter trips immediately.
2-11 Restart Delay
Range:
Function:
10
s
*
[00:01–
60:00
(min:s)]
The soft starter can be configured to force a
delay between the end of a stop and the
beginning of the next start. During the restart
delay, the display shows the time remaining
until another start can be attempted.
NOTICE
The restart delay is measured from the
end of each stop. Changes to the restart
delay setting take effect after the next
stop.
Parameter Descriptions
VLT
®
Soft Starter MCD 500
62
Danfoss A/S © 05/2016 All rights reserved.
MG17K602
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