Application Examples; Motor Overload Protection; Aac Adaptive Acceleration Control; Starting Modes - Danfoss mcd-500 Operating Instruction

MCD 500 Operating Instruction

5 Application Examples

5.1 Motor Overload Protection

Motor overload protection in the MCD 500 uses a second order thermal model. This calculates the motor temperature based on the thermal properties
of two components:
• Motor Body: This has a large thermal capacity and affects the long term behaviour of the motor.
• Motor windings: These have a low thermal capacity and affects the short term thermal behaviour of the motor.
The thermal model also takes into account the influence of motor current, iron losses, winding resistance losses, and different cooling rates during run
and at standstill.
The value displayed on the LCP is the value of the winding model as a percentage of the rated capacity of the motor.
The MCD 500 calculates the motor's thermal capacity based on the settings in
Motor FLC
Par. 1-1 should be set to the motor's rated FLC. Do not add the overload rating as this is computed by the MCD-500.

5.2 AAC Adaptive Acceleration Control

AAC Adaptive Acceleration Control is a new form of motor control based on the motor's own performance characteristics. With AAC, the user selects the
starting or stopping profile that best matches the load type and the starter automatically controls the motor to match the profile. The MCD 500 offers
three profiles - early, constant and late acceleration and deceleration.
AAC uses two algorithms, one to measure the motor's characteristics and one to control the motor. The MCD 500 uses the first start to determine the
motor's characteristics at zero speed and at maximum speed. During each subsequent start and stop, the starter dynamically adjusts its control to ensure
the motor's actual performance matches the selected profile throughout the start. The starter increases power to the motor if the actual speed is too low
for the profile, or decreases power if the speed is too high.

5.3 Starting Modes

5.3.1 Constant Current

Constant current is the traditional form of soft starting, which raises the current from zero to a specified level and keeps the current stable at that level
until the motor has accelerated.
Constant current starting is ideal for applications where the start current must be kept below a particular level.
3
700%
600%
500%
400%
300%
1
200%
100%
10% 20% 30% 40% 50%
Rotor speed (% full speed)
2
60% 70% 80% 90% 100%
MG.17.K2.02 - VLT ® is a registered Danfoss trademark
Primary Motor Set
.
1: Initial current (Par. 1-5)
2: Current limit (Par. 1-4)
3: Full voltage current
5 Application Examples
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