KUKA KR C4 Smallsize-2 family's smallest control cabinet

KUKA KR C4 Smallsize-2 family's smallest control cabinet

KUKA KR C4 smallsize-2 is a compact control cabinet launched by KUKA for applications involving small robots, linear units, and positioners. It can control up to 6 servo axes, weighs about 60 kg, has a protection level of IP54, and the cabinet adopts RAL 7016 side panels and KUKA orange cabinet doors. The control cabinet supports AC power supply of 3x380 V, 3x400 V, 3x440 V or 3x480 V, with a rated load of 3.3 kVA, a rated short-circuit current of 5 kA, and a system impedance not exceeding 300 m Ω. The recommended melting point for the main power supply is 3x32 A slow melting; If the drive box is not equipped, we recommend 3x16A slow melting. The operating environment temperature ranges from+5 ° C to+45 ° C, and the storage and transportation temperature ranges from -25 ° C to+40 ° C. When without a battery, the storage and transportation temperature can be extended to -25 ° C to+70 ° C. The controller only supports KSS V8.3.20 and above versions. For on-site engineers, mastering LED diagnosis, fuse specifications, driver unit replacement, control PC maintenance, and safety interface inspection is the key to shortening downtime.

System architecture and key components

The core of KR C4 smallsize-2 is the driving unit, which integrates KUKA Power Pack Small Robot and KUKA Servo Pack Small Robot internally. The driving unit is responsible for generating intermediate circuit voltage, controlling the motor, controlling the brake, and checking the intermediate circuit voltage in braking mode. The control PC is responsible for graphic interface, program creation and maintenance, sequence control, path planning, drive circuit control, monitoring, safety equipment, and external communication. Control PC can be equipped with D3236-K or D3445-K motherboard. D3236-K provides 7 fieldbus slots, LAN Onboard interface, USB 2.0/3.0, DVI-I; D3445-K provides fieldbus slots, LAN Onboard, USB, DVI-D, Display Port, and more. VGA can be achieved through an adapter, but external displays are only available when not connected to a smartPAD or virtual remote teaching pendant.

CCU_SR stands for Small Robot Cabinet Control Unit, which is the central power distribution and communication interface composed of CIB_SR and PMB. It is responsible for safety input/output, contactor activation, 4 floating outputs, 9 safety inputs, smartPAD insertion recognition, mastering testing, 6 rapid measurement inputs, external fan monitoring, power fan monitoring, and temperature detection inside the control cabinet. Connect the driver unit, RDC, and digital I/O module through the KUKA controller bus; Connect the operation panel interface, diagnostic LED, and EDS interface through the KUKA system bus. The power supply with battery backup includes a drive unit, an external fan smartPAD、 Multi core control PC, RDC; The power supply without battery backup includes motor brake and customer interface. The low-voltage power supply supplies power to the control cabinet components, and the green LED indicates the working status. The battery maintains controlled shutdown in the event of power failure and undergoes regular charging and load testing.

In terms of bus system, KCB includes driver units, RDC, CIB_SR, and EMD; KSB includes CIB_SR, SION, smartPAD, and extended SIB; Please refer to the optional interface document for KEB devices. The cooling system adopts a dual circuit design: the inner area is cooled by a controlled PC fan, while the outer area is directly cooled by an external fan for the ballast resistor, low-voltage power supply, and drive unit heat sink. The customer option space is located on the right side of the control cabinet, with a top cap guide rail structure that can accommodate bus modules, etc. It has a maximum power consumption of 20 W, a depth of approximately 200 mm, a width of 250 mm, and a height of 150 mm. The optional transient limiter consists of a base module and a plug-in protection module to suppress surge voltage.

Safety regulations and power-off operation

Before maintenance or replacement of KR C4 smallsize-2, five safety rules must be followed: power off, prevent accidental restart, confirm that the system is out of power, ground short circuit, and cover or isolate adjacent live parts. Wait for at least 5 minutes after power failure to allow the intermediate circuit to discharge. KPP_SR, KSP_SR, intermediate circuit cables, motor connections, and motor cables in the drive unit may still carry a voltage of 50 V to 330 V, and it must be confirmed that there is no power before operation. Wear protective gloves during operation, avoid contact with high-temperature radiators, and comply with ESD regulations. The main switch of the control cabinet cannot isolate the incoming power supply. The cable connecting power supply X1 to the main switch is always live and must be disconnected from the upper power supply. If power on operation is required, it can only be carried out in T1 mode and additional protection measures should be taken. The safety functions include operation mode selection, operator safety, emergency stop devices, enabling devices, external safety stops, and T1 speed monitoring, in compliance with EN ISO 13849-1 Category 3 and Performance Level d. The emergency stop device must be pressed at least once every 12 months.

Security interface X11 and US2 inspection

The X11 security interface is internally connected to CCU_SR, which is used for dual channel signals such as emergency stop, operator safety, safety stop 2, external enable, and safety operation stop. Test outputs A and B are pulse voltages that can only be used as safe inputs for the corresponding channels and cannot be used as regular power supplies. 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 safety input must use floating contacts, and the input channel SIN_X_A must be powered by TA_S, while SIN_X_B must be powered by TA-B. The safety output is a dual channel floating relay output that can be connected to the upper level safety PLC. The wiring example can achieve category 3 and PL d.

X11 External Enable Switch: External Enable 1 must be pressed when T1 or T2 is tapped, and the input is closed; External enable 2 must not be in the panic position, input closed. If external enable 1 is not connected, short circuit 11/12 of channel A and 29/30 of channel B; External enable 2 is not connected, short circuit 13/14 of channel A and 31/32 of channel B. If smartPAD is connected, its enable switch performs AND logic with external enable. Inspection of the USS load voltage contactor: In the PROFIsafe or CIP Safety configuration, set the USS input and the contactor is engaged; Reset the US2 input and disconnect the contactor. In automatic mode, press the enable switch to close the contactor and move the robotic arm; Release the enable switch and disconnect the contactor. In KRC configuration, operator safety can be turned on in automatic or automatic external mode, or the enable switch can be released in T1/T2 to check. Cross connection must be prevented between US1 and US2, and it is recommended to separate wiring or use reinforced insulated cables.

CCU_SR LED diagnosis

The LED on CCU_SR is the first-hand diagnostic information. PHY4 and SW-P0 are green, constantly on or flashing indicates normal, and off indicates a fault. Usually, CCU_SR needs to be replaced. RUNSION green indicates the status of the EtherCAT safety node: normally on for normal operation, off for initialization, flashing at 2.5 Hz for Pre Op, single signal for Safe Op, flashing at 10 Hz for firmware update boot. L/A KSB, L/A KSB KPC-MC, L/A KCB, L/A KSB smartPAD, etc. Green or orange colors indicate physical connections and data traffic: green is always on for physical connections, off for unconnected, and flashing for data traffic; Orange represents 1 Gbit, green represents 100 Mbit. PWR/3.3 V, PWR/2.5 V, and PWR/1.2 V are green power indicators. When turned off, check the F17-3, X308 jumper plugs, F308, and external 24V power supply; If PWR/3.3 V is on and PWRS/3.3 V is off, consider replacing CCU_SR. When PWRS/3.3 V is turned off, check F17-3. If PWR/3.3 V is on, replace CCU_SR. STAS2 and STAS1 are orange safety node indicator lights: check F17-3 when they are off, and replace CCU_SR if PWR/3.3 V is on; 1 Hz flicker is normal, 10 Hz flicker is the guiding phase; When the fault code flashes, check the X309, X310, and X312 cables. You can disconnect these cables and restart the controller. FSoE green indicates EtherCAT security protocol: off indicates inactive, constantly on indicates running, flashing indicates internal fault. RUN CIB_SR green indicates EtherCAT I/O node: normally on for running, off for initialization, flashing at 2.5 Hz for Pre Op, single signal for Safe Op, flashing at 10 Hz for firmware update. STA1 is an orange microcontroller I/O node: check F17-3 when it is turned off, and replace CCU_SR if PWR/3.3 V is on; 1 Hz flashing is normal, 10 Hz flashing guides, flashing is a fault code.

CCU_SR fuse quick check

The red LED of the fuse indicates that the fuse is damaged, and turning off indicates that it is normal. The same specifications must be used when replacing. F306 is the smartPAD power supply, 2 A; F302 is the I/O board power supply, 5 A; F3-1 is the KPP_SR and KSP_SR brake without battery backup, 15 A; F5-1 is the 24 V without battery backup option, 15 A; F4-1 is the KPC with battery backup, 10 A; F307 is the UL light optional, 2 A; F4-2 is the 24 V with battery backup fan, 2 A; F22 is the 24 V without battery backup option, 7.5 A; F5-2 is the 24 V with battery backup option, 7.5 A; F3-2 is the KPP_SR and KSP_SR logic with battery backup, 7.5 A; F17-2 is the CCU_SR input, 2 A; F17-4 is the CCU_SR input, 2 A; U_SR safety input and relay, 2 A; F17-1 CCU_SR contactor output 1 to 4, 5 A; F17-3 CCU_SR logic, 2 A; F14 external fan optional, 7.5 A; F6 I/O board power optional, 7.5 A; F21 RDC power supply, 3 A; F305 battery feed, 15 A; F301 24 V No battery backup option, 10 A; F15 is the power fan, 2 A; F308 is the external power supply, 7.5 A. When troubleshooting, first check the fuse LED, then measure the voltage, and finally consider module replacement.

Drive unit and control PC maintenance

Before replacing the drive unit, it is necessary to disconnect the power, hang out the tag, wait for 5 minutes, and confirm that there is no power. Unplug all connections, loosen the 2 knurled screws on the front of the drive unit, hold the handle and pull it forward. When installing a new driver unit, place it on the support rail, tighten the rolling screws, insert all connections back according to the label, and start the controller to observe any abnormalities. When replacing the control PC, first shut down by cold start and reloading files, turn off the main switch and prevent restart, and disconnect the power cable. Unplug all connections of the control PC, loosen the knurled nut, and remove it upwards. After installing a new PC, plug it back in and start the controller. Starting from KSS 8.3 and D3236-K, after successful startup, disconnect the Board Package USB and save it properly. Driver installation may take time. When replacing the PC fan, remove the control PC, remove the air duct, open the casing, unplug the fan connection, remove the outer grille, fan, and inner grille, install a new fan, and restore it. When replacing the SSD, loosen the knurled screws, unplug the SATA and power connections, install the operating system and KSS after replacing the disk, and configure the system through WorkVisual. Replacing the motherboard battery can only be carried out by authorized maintenance personnel with the support of KUKA; Mainboard faults are usually replaced with the control PC as a whole. When replacing the battery, both battery blocks must be replaced simultaneously, paying attention to polarity to prevent short circuits. When replacing the low-voltage power supply, main filter, ballast resistor, and CCU_SR, it is necessary to cut off the power, discharge, unplug the connection, remove the fixing, replace the new parts, restore the wiring, and test. Surge resistance inspection: measured at X3 of KPP_SR, X3.1 to X3.2 should be 20.4 to 23.8 Ω; If the resistance value does not match and the cable is normal, replace the ballast resistor.

Maintenance cycle and cleaning

The maintenance of KR C4 smallsize-2 should be carried out on a periodic basis. Inspect the relay outputs used by CCU_SR annually and conduct operator safety function tests on external emergency stop devices. Clean the external fan protective grille and drive cooling fins at least annually based on the level of pollution. Clean the external fan, low-voltage power radiator, and control cabinet interior every 2 years. Replace the motherboard battery, control the PC fan, and external fan every 5 years; The battery replacement cycle depends on the battery monitoring indication. After maintenance, visually inspect the fuses, contactors, plugs, and boards for secure installation, no damage to cables, reliable PE equipotential connections, and no wear or damage to system components. When cleaning, the power must be turned off and wait for 5 minutes. Use solvent-free, water-soluble, non flammable, and non corrosive cleaning agents. Do not use compressed air, spray water, or allow cleaning agents to enter electrical components. Replace damaged or unreadable labels and nameplates after cleaning.