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EN 60204-1: What issues do we need to pay attention to?
Created on 03.07
EN 60204-1 (Full name: Safety of machinery - Electrical equipment of machines - Part 1: General requirements) is the core standard for electrical safety design of mechanical products.
1. Disconnecting Devices and Switching Off Power
This is the first line of defense for electrical safety, and the standard has very detailed regulations on "how to disconnect power":
- Main Disconnecting Device:
- Each machine must have a main switch that can disconnect all live conductors (including the neutral conductor, if there is a risk).
- Must have a clear indication of the disconnected position (visible break or reliable position indicator).
- Must be lockable in the "OFF" position (usually supports padlocks) to prevent accidental re-energization.
- Capacity requirements: Must be able to withstand the machine's maximum operating current and short-circuit current.
- Prevention of Unexpected Start-up:
- The machine must not restart automatically when power is restored.
- Control circuit design must prevent accidental startup due to voltage fluctuations or signal interference.
- Residual Energy Discharge:
- After power-off, energy storage components such as capacitors must discharge voltage to below 60V within 5s.
- If automatic discharge is not possible, there must be a clear warning label and instructions for manual discharge procedures.
2. Protection Against Electric Shock
- Direct Contact Protection: All live parts must be enclosed by a casing (minimum IP2X rating, i.e., not touchable by fingers).
- All live parts must be enclosed by a casing (minimum IP2X rating, i.e., not touchable by fingers).
- Or installed at a height/position out of reach.
- Indirect Contact Protection: Protective Earth (PE): All conductive non-live metal parts (motor housing, cabinet, door panels) must be reliably earthed.
- Protective Earth (PE): All conductive non-live metal parts (motor housing, cabinet, door panels) must be reliably earthed.
- Grounding continuity: The resistance of the protective grounding circuit must be sufficiently low (usually requiring the entire loop impedance < 0.1Ω or compliance with specific calculation formulas) to ensure that fuses/circuit breakers operate quickly in case of a fault.
- Equipotential bonding: Equipotential connection must be made between all metal parts within the machine to eliminate potential differences.
- Insulation requirements:
- Basic insulation must be able to withstand the requirements of the rated voltage and overvoltage category (usually Cat. III).
- For hand-held operating parts, double insulation or reinforced insulation may be required.
3. Control Circuits and Safety Functions
This is the most strictly audited part, directly related to personnel safety:
- Emergency Stop Function:
- Must comply with Category 0 (immediate power cut-off, e.g., cutting off the contactor coil) or Category 1 (controlled stop followed by power cut-off).
- Emergency stop buttons must be red mushroom head, yellow background, and have a direct breaking action (positively opening contact).
- After the emergency stop is reset, the machine must not restart automatically; it must be operated via a dedicated "Start" button.
- Safety Circuit Design:
- For high-risk functions (e.g., safety gates, light curtains, two-hand buttons), the control circuit must achieve the corresponding Performance Level (PL) (according to ISO 13849-1).
- Single Fault Principle: Circuit design must ensure that a single component failure (e.g., contact sticking, open circuit) does not lead to the failure of the safety function. Dual-channel redundant design with cross-monitoring is typically used.
- Control Voltage:
- Safety Extra-Low Voltage (SELV/PELV), such as DC 24V, is recommended to reduce the risk of electric shock and arc energy.
- If high voltage control is used, additional protective measures must be in place.
4. Wiring and Cabling
- Cable Selection:
- Flame-retardant, oil-resistant, and corrosion-resistant industrial cables (e.g., H07RN-F, CY/JZ, etc.) must be used.
- Cables for moving parts (e.g., drag chains) must be high-flexibility special cables.
- Color Coding: Strictly adhere to standard color codes, mixing is strictly prohibited:
- Black: AC Power Circuit.
- Red: AC Control Circuit.
- Blue: DC Control Circuit.
- Yellow/Green: Protective Earth (PE), strictly prohibited for other uses.
- Orange: Externally interconnected power circuits (parts that may remain live even when de-energized, such as robot end-of-arm tooling).
- Wiring Practices:
- Power and signal lines must be routed separately or shielded to prevent electromagnetic interference.
- Harnesses must be securely fixed to avoid abrasion.
- Protective grommets must be installed when passing through metal holes.
5. Components and Equipment Selection
- CE Compliance: All electrical components (circuit breakers, contactors, PLCs, sensors, etc.) must comply with CE requirements themselves and meet relevant harmonized standards.
- De-rating: Components must operate within their rated parameters, with a margin usually recommended (e.g., current load not exceeding 80% of rated value).
- Environmental Adaptability: The IP rating and temperature rating of components must meet the machine's actual operating environment (e.g., high temperature, high humidity, dust).
6. Marking and Documentation
- Warning Labels:
- "Danger Voltage" label (lightning symbol).
- "Emergency Stop" label.
- "Rotation Direction" label.
- If there are still live parts after power is disconnected, "Wait X minutes" or "Live parts" must be marked.
- Technical Documentation:
- Electrical schematic diagram: Clear, complete, and compliant with IEC graphical symbol standards.
- Layout and wiring diagrams: Show actual installation positions and wiring details.
- Bill of Materials (BOM): Includes model, specifications, and manufacturer.
- Calculation reports: Short-circuit current calculation, grounding resistance calculation, voltage drop calculation.
- Test records: Electrical test reports before factory shipment.
EN 60204-1 is not just a design guide; it is the baseline for legal compliance.
- Design phase: Color codes, grounding specifications, and emergency stop categories must be strictly followed.
- Manufacturing Stage: Wiring process and component quality must be guaranteed.
- Acceptance Stage: Electrical tests must be completed and records retained.
- Documentation Requirements: Generate corresponding technical documents and reports and save them.