Safety Notice: Risk of Unexpected Motion and Electrical Shock During Maintenance on CLR032-004 Robots

Related Products

Tools Required

• Authorized personal safety lock
• Lockout/Tagout tag
• Calibrated voltmeter (rated for 480VAC or higher)
• Personal Protective Equipment (PPE) including voltage-rated gloves and safety glasses

Article

This document provides mandatory safety procedures for all personnel performing maintenance, service, or repair on the NexBot Robotics CLR032-004 Cleanroom SCARA Robot. Failure to adhere to these procedures can result in unexpected robot motion, electrical shock, or other hazards, leading to serious injury or death. All maintenance activities must be performed by qualified and authorized personnel who have been trained in lockout/tagout (LOTO) procedures.

Hazard Identification

The NXB-ROB-CLR032-004 system contains multiple energy sources that must be controlled before any service is performed.

• Unexpected Motion: The robot arm can move unexpectedly even when the controller is seemingly off. This can be caused by stored electrical energy in servo drive capacitors, stored pneumatic pressure in end-of-arm tooling (EOAT), or kinetic energy from an unbalanced mechanical load. All four axes (J1, J2, J3, J4) are capable of high-speed motion.
• Electrical Shock: The robot controller and associated servo drives operate on 200-240VAC. Internal components, particularly capacitors within the servo drives (e.g., NXB-SRV-AC111-004), can retain a lethal electrical charge for several minutes after the main power has been disconnected.

Affected Products

These procedures apply to the following product and all systems in its series:

• Primary Product: NXB-ROB-CLR032-004 - NexBot Robotics CLR032-004 Cleanroom SCARA Robot 5kg
• Product Series: NexBot S-3 Series SCARA Robots

Required Safety Procedure: Lockout/Tagout (LOTO)

Follow this procedure strictly before accessing any part of the robot's mechanical or electrical systems.

Step 1: Preparation for Shutdown

1. Notify Personnel: Inform all operators and affected personnel in the area that the robot will be shut down for maintenance.
2. Identify Energy Sources: Identify all sources of energy for the robot system. This includes the main electrical disconnect for the robot controller, as well as any separate pneumatic or hydraulic supplies (e.g., NXB-GEN-PNU411-006).
3. Gather LOTO Equipment: Ensure you have an authorized safety lock, a durable tag, and a calibrated voltmeter rated for the system voltage.

Step 2: Robot Shutdown

1. Stop Operation: Bring the robot to a complete stop using the standard operating procedure.
2. Position Arm: Move the robot arm to its designated home position or a stable, mechanically-sound maintenance position. This prevents uncontrolled movement due to gravity when power is removed.
3. Power Down Controller: Shut down the robot controller using the power button or software interface.

Step 3: Isolate Energy Sources

1. Main Electrical: Locate the main electrical disconnect switch for the robot controller (e.g., NXB-GEN-841-003). Move the switch to the OFF position.
2. Pneumatic/Other: If applicable, shut off and isolate the main pneumatic supply valve.

Step 4: Apply Lockout/Tagout Devices

1. Apply Lock: Attach your assigned personal safety lock to the main electrical disconnect switch in the OFF position. If the disconnect cannot be locked directly, use a lockout device (e.g., a breaker lock).
2. Apply Tag: Attach a completed LOTO tag to your lock. The tag must clearly state your name, the date/time, and a brief description of the work being performed.

Step 5: Dissipate and Control Stored Energy

1. Electrical Discharge: WAIT A MINIMUM OF 5 MINUTES after isolating power. This allows time for the capacitors within the servo drives to discharge. Do not proceed until this time has elapsed.
2. Verify Zero Energy State (Electrical):

• Put on appropriate Personal Protective Equipment (PPE), including voltage-rated gloves and safety glasses.
• Open the controller cabinet door.
• Using a calibrated voltmeter, carefully test the incoming power terminals (L1, L2, L3) to verify zero voltage. Test phase-to-phase and phase-to-ground.
• If any voltage is detected, STOP. Do not proceed. Re-evaluate the energy isolation point.

1. Verify Zero Energy State (Pneumatic): If pneumatic systems are present, bleed all lines by activating the manual override on the solenoid valves. Visually confirm that all pressure gauges read zero.
2. Control Mechanical Energy: If the robot arm is in a raised position, consider using mechanical blocks or supports to prevent it from falling due to gravity or external forces.

Step 6: Verify Isolation (Try-Out)

1. Attempt Startup: With all personnel clear of the robot, attempt to power on the robot controller using the normal start button.
2. Confirm Failure: Verify that the controller does not power on and the robot does not move. This is the final confirmation that the system is properly isolated.
3. Return the start button to the OFF position.

The robot is now in a zero-energy state and is safe for maintenance.

Restoring Equipment to Service

1. Inspect Area: Ensure all tools, parts, and equipment have been removed from the robot work envelope. Reinstall all safety guards and panels.
2. Notify Personnel: Inform all affected personnel that the robot is being returned to service.
3. Remove Devices: The employee who applied the LOTO devices is the only person authorized to remove them. Remove your tag and then your lock.
4. Restore Energy: Restore energy by turning the main electrical disconnect to the ON position and reopening pneumatic valves.
5. Follow Standard Startup: Power on and initialize the robot according to the official operating manual.

Your safety is paramount. Never bypass or ignore LOTO procedures. If you are unsure about any step, consult your supervisor or a qualified safety professional.

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