Danfoss mcd-500 Operating Instruction

Also see for vlt soft starter mcd 500: Installation instructions Installation instructions Installation instructions Installation guide Installation guide

Contents

Danfoss mcd-500 Operating Instruction Manual pdf 33 page image

5 Application Examples5.1 Motor Overload ProtectionMotor overload protection in the MCD 500 uses a second order thermal model. This calculates the motor temperature based on the thermal propertiesof 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 runand 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 inPrimary Motor Set.Par. 1-1Motor FLC 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 ControlAAC Adaptive Acceleration Control is a new form of motor control based on the motor's own performance characteristics. With AAC, the user selects thestarting or stopping profile that best matches the load type and the starter automatically controls the motor to match the profile. The MCD 500 offersthree 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 themotor's characteristics at zero speed and at maximum speed. During each subsequent start and stop, the starter dynamically adjusts its control to ensurethe motor's actual performance matches the selected profile throughout the start. The starter increases power to the motor if the actual speed is too lowfor the profile, or decreases power if the speed is too high.5.3 Starting Modes5.3.1 Constant CurrentConstant 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 leveluntil the motor has accelerated.Constant current starting is ideal for applications where the start current must be kept below a particular level.700%600%500%300%100%400%200%10% 20% 30% 40% 50%Rotor speed (% full speed)60% 70% 80% 90% 100% 177HA289.11Current (% motor full load current)1321: Initial current (Par. 1-5)2: Current limit (Par. 1-4)3: Full voltage currentMCD 500 Operating Instruction 5 Application ExamplesMG.17.K2.02 - VLT® is a registered Danfoss trademark 335