The NORD SK 500E series frequency inverters are designed for industrial and commercial systems, offering compact design, optimal control characteristics, and uniform parameterization. These devices are suitable for operating three-phase asynchronous motors with squirrel-cage rotors and Permanent Magnet Synchronous Motors (PMSM), provided the motors are compatible with frequency inverter operation. Other loads should not be connected. The SK 5xxE frequency inverters are intended for stationary installation in control cabinets, with all technical data and permissible installation conditions needing to be observed. Commissioning is only permitted after ensuring compliance with the EMC Directive 2004/108/EEC (2014/30/EU as of 20.04.2016) and the Machinery Directive 2006/42/EEC (EN 60204).
Function Description:
The SK 500E series features sensor-less current vector control with a wide range of settings. This allows for high starting and overload torques with constant speed. The performance range extends from 0.25 kW to 160.0 kW. Modular assemblies enable adaptation to individual customer requirements.
Key properties include:
- High starting torque and precise motor speed control with sensorless current vector control.
- Ability to be mounted next to each other without additional spacing.
- Automatic measurement of stator resistance or determination of precise motor data.
- Programmable direct current braking.
- Integrated brake chopper for 4-quadrant operation (optional brake resistors).
- Four separate online switchable parameter sets.
- RS232/485 interface via RJ12 plug connector.
- Integrated USS and Modbus RTU protocols.
Important Technical Specifications:
- Operating Voltage: Inverters for 230V or 400V are typically supplied with an integrated mains filter. 115V inverters are usually supplied without mains filters.
- EMC Mains Filter: SK 5xxE-...-A types include an integrated EMC mains filter for limit curve A1 (and B1 for sizes 1-4) according to EN 55011, Category C2 (and C1 for sizes 1-4) according to EN 61800-3 (not for 115V inverters). SK 5xxE-...-O types are supplied without an integrated EMC mains filter, having reduced X2-capacitors for basic interference reduction.
- Ambient Temperature: Permissible range is 0 to 50°C.
- Digital Inputs/Outputs: SK 50xE, 51xE, 511E, 520E, 53xE models offer 5/0 or 7/2 digital I/Os. SK 54xE models offer 5/3, 6/2, or 7/1 digital I/Os, with 2 I/Os variably parameterizable.
- Analog Inputs/Outputs: 2/1 for all models.
- Relay Messages: 2 for all models.
- Safe Pulse Block (STO/SS1): Available for all models except 115V devices.
- CANbus/CANopen Interfaces: 2 x RJ45 interfaces are standard for size 5 and above, and optional for other models.
- RS485 Interface: Additionally available via terminals for 511E, 520E, 53xE, and 54xE models.
- Speed Feedback: Incremental encoder input for 511E, 520E, 53xE, and 54xE models.
- Integrated POSICON Positioning Control: Available for 53xE and 54xE models.
- PLC/SPS Functionality: Available for 53xE and 54xE models.
- Universal Encoder Interface: Available for 54xE models (SSI, BISS, Hiperface, EnDat, SIN/COS).
- PM Synchronous Motor Operation: Available for all models.
- Additional Potential-Isolated PTC Input: Available for 54xE models (alternative "thermistor" function on digital input 5 possible; above size 5 an additional thermistor input is standard).
Usage Features:
- Installation: Devices are mounted directly on the rear wall of a control cabinet. Wall-mounting brackets are supplied for sizes 1-7, while for size 8 and above, the mounting device is integrated. Vertical mounting is recommended for optimal convection.
- ColdPlate Version: For sizes 1-4, a ColdPlate version is available, featuring a flat metal plate on the rear for thermal conduction, allowing waste heat to be dissipated externally. This reduces installation depth and often eliminates the need for a fan. External heat sink kits (SK TH1-...) are available for ColdPlate versions if a liquid-cooled mounting plate is not used.
- Brake Resistors (BR): External brake resistors (SK BR4-... bottom-mounted, IP54; SK BR2-... chassis-mounted, IP20) can be used to prevent overvoltage shutdowns during dynamic braking. For inverter powers up to 7.5 kW (230V: up to 4.0 kW), bottom-mounted resistors are used. For powers above 3kW, chassis-mounted resistors are available.
- Chokes: Input chokes (SK CI1-...) and link circuit chokes (SK DCL-...) provide mains protection by reducing harmonics and charging currents. Output chokes (SK CO1-...) reduce interference from motor cables.
- Line Filters: External line filters (SK NHD, SK LF2, SK HLD) can be installed to maintain increased noise suppression levels (Class B as per EN 55011).
- Electrical Connection: Detailed wiring guidelines are provided for EMC-compliant installation, including shielding, earthing, and separation of control and power cables.
- DC-Coupling: Advisable for systems where motors act as drivers and generators simultaneously, allowing energy transfer between drives and reducing the need for braking resistors.
- Control and Parameterization: The SimpleBox (SK CSX-0) offers a 4-digit, 7-segment LED display and single-button operation for basic parameterization and control. The PotentiometerBox (SK TU3-POT) allows direct control from the device. Various technology units (SK TU3-CTR, SK TU3-PAR) and bus interfaces (AS-Interface, CANopen, DeviceNet, InterBus, Profibus DP, EtherCAT, Ethernet/IP, Profinet IO, Powerlink) are available for more complex tasks and integration into automation systems.
- Parameter Settings: All parameters are factory-set for a 4-pole IE1 three-phase motor with the nominal FI power setting. Parameters can be adjusted online, with four switchable parameter sets available during operation. P523 allows loading factory settings at any time.
- Motor Control Operating Modes: Includes VFC open-loop mode (P300=0) for sensorless control, CFC closed-loop mode (P300=1) for precise speed and position control with an encoder, and CFC open-loop mode (P300=2) for operation without an encoder using "observation" of measurements.
- KTY84-130 Connection: For optimized current vector control, a KTY84-130 temperature sensor can be used to measure motor temperature directly.
- Frequency Addition/Subtraction: Via operating boxes (ControlBox or ParameterBox) for software version 1.7 and above.
Maintenance Features:
- Maintenance-Free: NORD frequency converters are maintenance-free under proper usage.
- Dusty Environments: Cooling-vane surfaces should be regularly cleaned with compressed air.
- Long-Term Storage: For storage longer than one year, devices must be re-commissioned with an adjustable transformer before normal mains connection. Specific regeneration processes are outlined for different storage durations and mains voltages.
- Service Notes: Technical support is available, and devices needing repair should be sent to NORD Electronic DRIVESYSTEMS GmbH. It is recommended to back up parameter settings before sending the device for repair. Optional modules should also be returned in case of a device fault.
- Monitoring: Brake resistor load can be monitored thermally with a temperature switch or indirectly via current measurement and calculation. The latter is based on standard ambient conditions and resets upon device shutdown, making a temperature switch the more reliable method for continuous monitoring.
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