KUKA KR C4 extended assembly and debugging

KUKA KR C4 extended assembly and debugging

KUKA KR C4 extended and KR C4 extended CK are high-performance control cabinets for medium to large robot systems, capable of controlling up to 16 axes, weighing up to approximately 240 kg, with a protection level of IP54 and an average noise level of approximately 65 dB (A). It is suitable for KUKA industrial robots, linear units, positioners, and motion systems that comply with DIN EN ISO 10218-1. The control cabinet adopts a modular architecture and is internally integrated KUKA Power Pack、KUKA Servo Pack、Control PC、Cabinet Control Unit、Safety Interface Board、Resolver Digital Converter、Controller System Panel、 Low voltage power supply, battery, main filter, fan, and connection panel. The quality of on-site assembly directly determines the stability, safety, and maintenance costs of the system in the future. This article forms a practical guide for on-site engineers from the perspectives of system composition, interface layout, motor connection, safety interface, PE equipotential, power connection, startup debugging, and common problem handling.

System composition and key modules

The core driver power supply of KR C4 extended is completed by KUKA Power Pack, also known as KPP. KPP rectifies the AC power supply into an intermediate circuit voltage, which is supplied to the internal drive controller and external drive. It has four variants: shaftless amplifier version, single axis 40 A, dual axis 40 A, three-axis 20 A, and single axis 64 A. KPP has a power output of 14 kW under 400 V power supply, rated current of 25 A DC, integrated brake chopper, external brake resistor activation, brake resistor overload monitoring, and synchronous servo motor short-circuit braking. KUKA Servo Pack, also known as KSP, is a drive controller for robotic arm shafts, available in three variants: three-axis 40 A, three-axis 64 A, and three-axis 20 A, with a power range of 11 kW to 14 kW per axis, using magnetic field oriented control.

The Cabinet Control Unit, also known as CCU, is the central power distribution and communication interface of the control cabinet, consisting of CIB and PMB. CCU is responsible for safety input and output, main contactor control, mastering testing, smartPAD recognition, rapid measurement input, fan monitoring, and temperature detection. If the main power supply fails, the battery will continue to supply power to the control components until the position data is saved and the controlled shutdown is completed. The Safety Interface Board (SIB) is a component of the safety interface. The standard SIB has 5 safety inputs and 3 safety outputs, while the extended SIB has 8 safety inputs and 8 safety outputs. The Resolver Digital Converter, also known as RDC, is used to detect motor position data and can connect up to 8 rotary transformers to measure motor temperature. Controller System Panel, also known as CSP, is an operational status display component with USB, KSI, and other connections. The control cabinet is also equipped with a low-voltage power supply, 24V external power interface, battery, fan, main filter, and connection panel.

The layout of the front and back of the control cabinet is clear: the front includes the connection panel, battery, fuses Q3/Q13, main switch, internal fan KSP T12/T11/T2/T1、KPP G11/G1、 Brake filters K12/K2, CSP, Control PC, SIB/Extended SIB, and CCU. The back includes an external fan, low-voltage power supply, braking resistor, heat exchanger, and main filter. The control cabinet can be equipped with a roller set for easy insertion and extraction in the cabinet. The cooling system is divided into two circuits: the inner zone contains control and power electronics, which are cooled by a heat exchanger; The braking resistor and KPP/KSP radiator in the outer area are directly cooled by ambient air. Do not install filter cotton upstream of the ventilation duct, otherwise it will cause temperature rise and shorten equipment life.

Interface layout and motor connection

The standard configuration of the KR C4 extended connection panel includes power connection X1, motor interface, option interface, X13 interface, X11 safety interface, X19 smartPAD connection, X21.1 RDC connection 2, X42 connection, X21 RDC connection 1, PE1 robotic arm grounding, and PE2 main power grounding. Security interface X11 and Ethernet security interface X66 cannot be connected and used simultaneously, only one can be selected. All contactors, relays, and valve coils connected by users must be equipped with suitable suppression diodes, RC components, and VCR resistors are not applicable.

The motor interface is the key to assembly. KR C4 extended supports multiple motor connector combinations, including X20, X20.1, X20.4, X7.1 to X7.6, X81, X82, X83, X84, etc., covering up to 16 axes. X20 is used for shafts 1 to 6, and connector inserts A to F correspond to KSP T2/T1 and KPP G1, respectively. X20.1 and X20.4 are used for heavy-duty robots, with X20.1 corresponding to axes 1 to 3 and X20.4 corresponding to axes 4 to 6. X81 is a multi connector that can connect 3 to 4 external axes; X82 is used for 8-axis expansion; X83 and X84 are used for higher axis configurations. Single connectors X7.1 to X7.12 are used for external axes, with each connector corresponding to one axis. Motor cables must use shielded cables, with a fixed installation bending radius of 3 to 5 times the cable diameter, and 7 to 10 times the cable drag chain. The total length of motor cables shall not exceed 50 meters. The length difference of cables in each channel of the RDC box shall not exceed 10 meters. The SmartPAD cable extension can be up to two, with a total length not exceeding 50 meters.

The control PC can be equipped with D3076-K, D3236-K, or D3445-K motherboards. D3076-K provides 7 fieldbus slots LAN Dual NIC、 4 USB 2.0, DVI-I, and LAN Onboard. D3236-K offers 7 fieldbus slots, 2 USB 3.0, DVI-I, 4 USB 2.0, and LAN Onboard. D3445-K offers 7 fieldbus slots, 2 USB 3.0, DVI-D, Display Port, 4 USB 2.0, and LAN Onboard. VGA can be achieved through an adapter, but external displays are only available when not connected to a smartPAD or virtual remote teaching pendant. The bus system includes KCB, KSB, and KEB. KCB connects KPP, KSP, RDC, CIB, and EMD; KSB connects CIB, SION, smartPAD, and SIB; KEB can connect devices such as PROFIBUS, DeviceNet, digital/analog I/O, EtherCAT bridging, etc. EtherCAT slave can be connected via X44 on CIB or can be exported via optional X65. X66 is a KUKA Line Interface used for external computer connections. X69 is the KUKA service interface used for diagnosis and WorkVisual configuration.

Security Interface X11 and Ethernet Security

The X11 security interface is a 50 pin D-Sub connector, which is internally connected to SIB. In the default configuration, test outputs A and B provide pulse voltage, which is only used for the safety input of the corresponding channel and cannot be used as a regular power supply. External emergency stop channels A and B are dual channel inputs with a maximum voltage of 24 V. Operator safety channels A and B are used for the safety door locking mechanism. Confirm the operator's safety input for confirmation after the safety door is closed. Safe operation stop channels A and B are used for static monitoring. Safe stop 2 channels A and B are used to trigger stop 2 and static monitoring. External Enable 1 and 2 are used for external dual channel enable switches. The local emergency stop output is a floating contact that closes when the smartPAD emergency stop is not pressed and the controller is turned on and running. Confirm that the output can be used to safely forward the operator to other robot controllers on the same safety fence. Peri enabled output is set to 1 when the driver is turned on, the safety controller motion enable exists, and the "Operator Safety Open" message is not activated.

During dynamic testing, the test output is alternately turned off, with a turn off pulse length t1 of 625 μ s and a range of 125 μ s to 2.375 ms. The time t2 between two turn off pulses on the same channel is 106 ms, and the offset t3 between two turn off pulses on the same channel is 53 ms. The input channel SIN_X_A must be powered by TA_S, and SIN_X_B must be powered by TA-B. The safety output is a dual channel floating relay output, and the power supply must come from a safety isolated PELV power supply. When wiring, input signals and test signals, output signals and test signals must be separated to prevent cross connections. The wiring example can achieve category 3 and performance level d.

The Ethernet safety interface X66 supports PROFIsafe or CIP Safety. The input byte 0 contains reserved bits, external emergency stop, operator safety, confirmation, safety stop 1, and safety stop 2. Output byte 0 contains local emergency stop, drive enable, motion enable, enable signal, Peri enabled, AUT, T1 and T2 modes. It is recommended to preset the input to 1 to prevent unexpected activation of new security features after software updates, which may cause downtime. SafeOperation can be used through an Ethernet secure interface, with input bytes including mastering testing, slowing down, stopping secure operations, monitoring space, and tool selection; The output bytes include SO, RR, JF, VRED, SBH, and MR. In input byte 2, JR is the master test input, VRED is activated to reduce speed, and SBH1 to 6 are axis group safety operation stops. In output byte 2, SO represents the security option activation status, RR represents the robot has been referenced, and JF represents the mastering error. In output byte 3, SBH5 to 6 and SOS are used for safe operation stop status. The safety function complies with EN ISO 13849-1 Category 3 and Performance Level d, with a PFH value of less than 1 x 10 ^ -7.

PE equipotential and power connection

PE equipotential connection is a necessary task before assembly. Connect the robot motion system and robot controller using a 16 mm ² cable. Use a 16mm ² PE conductor to connect the central PE row of the power supply cabinet and the PE bolt of the controller. If a drive box is installed on the KR C4 extended, a 16 mm ² PE conductor needs to be connected between the drive box and the workshop equipotential. After installation, a fault circuit impedance test must be conducted in accordance with section 18.2.2 of EN 60204-1.

The power connection is completed through the X1 Harting connector. The control cabinet can only be connected to a power system with a grounded neutral point. The rated voltage can be selected from 3x380 V AC and 3x400 V AC, with a permissible deviation of ± 10%. The frequency is between 49 and 61 Hz, and the system impedance does not exceed 300 m Ω. The ground leakage current of KPP G1 can reach 300 mA, and KPP G1 and G11 can reach 600 mA. The short-circuit current rating is 25 kA at 480 V AC and 20 kA at 575 V AC. The main power supply is fused: a minimum of 3x25 A slow melting is required for KPP G1 only; Minimum 3x50 A slow melting for KPP G1 and G11. If using RCCB, attention should be paid to the residual current that may exist during fault free operation. RCCB is used for equipment protection rather than personnel protection, and it is recommended to use universal current sensitive and selective models. Before connecting the power supply, it is necessary to cut off the power, hang a tag, confirm that there is no power, and follow the five step safety rules.

Installation conditions, transportation, and start-up debugging

The control cabinet can be installed in a 19 inch rack or used as a standalone device. The rack depth must be at least 600 mm. A 70 mm cooling air gap must be maintained on both sides. Minimum clearance: top 300mm, side 50mm, rear 100mm. Cabinet door opening range: independent cabinet about 180 °, combined cabinet about 155 °. The size of the floor mounting hole is 750 x 482 mm, with M8 screws. The installation holes for the technical cabinet are 4x M10 blind holes with a spacing of 722 x 405 mm. The welding cabinet is compatible with guide rail holes of M10, with a spacing of 95mm and a guide rail length of 450mm.

During transportation, the control cabinet must be closed, cables must not be connected, and kept upright. Four M10 DIN 580 lifting rings are used for hoisting, with a load-bearing capacity of 230 kg. Forklifts, pallet trucks, or roller sets can be used. Avoid vibration and impact during transportation to prevent poor contact of PC card insertion. During installation, check the control cabinet for any transportation damage, confirm that the fuses, contactors, and boards are securely installed, tighten all screws and clamp connections. Before starting, ensure that there is no condensation and that the temperature inside the cabinet is balanced with the ambient temperature.

Startup sequence: Install the control cabinet, connect the PE, connect the motor cable and data cable, insert the smartPAD into X19, restore the battery discharge protection connector X305 to CCU, configure the X11 safety interface, connect the power supply, and turn on the device. Before starting, it is necessary to check the machine data, safety configuration, and brake testing. Security configuration checks include emergency stop, enable, operator safety, external safety stop, etc. Functional testing must cover local emergency stop, external emergency stop, enabling devices, operator safety, and other safety inputs and outputs. If the machine data or security configuration is modified, actual testing must be conducted again. System configuration modifications must use WorkVisual, including installing KSS/VSS 8.2 or higher, replacing hard drives, changing devices of different models, and removing or adding devices. Devices of the same type can be replaced, but two identical components in KCB cannot be replaced simultaneously, except for KSP3x40. The startup mode is used to move the robotic arm in T1 mode when the external safety device has not been installed or put into operation. At this time, all outputs are automatically set to logic zero, the external safety device is disabled, and no one is allowed in the danger zone. In T1 mode, the axis speed monitoring defaults to a rotation axis of 30 °/s, a linear axis of 250 mm/s, and a Cartesian speed of 250 mm/s.

Common problems and solutions

Common on-site issues include: cross connection of safety interfaces leading to failure of safety functions, requiring separate wiring for input/testing and output/testing signals. Poor PE equipotential can cause communication interference or safety signal misoperation, and the impedance of the 16 mm ² connection and faulty circuit must be checked. The deep discharge of the battery causes the controller to be unable to shut down under control, and it needs to be charged regularly according to the storage temperature: no higher than+20 ° C every 9 months,+20 ° C to+30 ° C every 6 months, and+30 ° C to+40 ° C every 3 months. Incorrect interface insertion leads to data errors. X20, X21, X21.1, X19, X11, and X66 must be connected according to the cable markings. If the motor cable is too long or the RDC channel length difference is too large, it may cause communication abnormalities, and the 50m and 10m limits must be followed. The disconnection of smartPAD triggers an emergency stop, and an external emergency stop must be connected and the disconnected smartPAD must be immediately removed. After the safety door is closed, it cannot directly resume automatic operation and must be confirmed through an external confirmation button. When the external enable is not connected, the corresponding terminals must be short circuited: external enable 1 short circuits channel A 11/12 and channel B 29/30; External enable 2 short circuits channel A 13/14 and channel B 31/32. When using Ethernet secure interfaces, shutting down the controller will not trigger an emergency stop for the entire system, and the system integrator must consider this in the risk assessment.

During maintenance and cleaning, it is necessary to disconnect the power, hang out the tag, and wait for the intermediate circuit to discharge. After the control cabinet is powered off, there may still be a voltage of 50 V to 780 V within 5 minutes, and it must be confirmed that there is no power. Comply with ESD regulations to prevent static electricity from damaging electronic components. Do not use compressed air, spray water, or allow cleaning agents to enter electrical components during cleaning. Replacement parts must use original factory spare parts. The safe lifespan of the system is 20 years, and the PFH value of KR C4 extended is less than 1 x 10 ^ -7. Through standardized assembly, correct wiring, rigorous testing, and rapid problem resolution, KUKA KR C4 extended can maintain long-term reliable operation in multi axis, high load robot applications.