Introduction to Machine Electrical Equipment
- Machines must follow safety standards when using electricity
⚡ These standards help protect people, machines, and materials. - DIN EN 60204-1 (VDE 0113-1) gives the rules for electrical equipment on machines
⚙️ It applies when there’s no other specific product standard. - Risk assessments help decide how dangerous a machine might be
🚧 Every machine type needs a safety check before use.
Main Switches (Mains Isolating Devices)
- Every machine needs a manual main switch
🛑 This switch turns off all electricity to the machine. - It must break power to the biggest motor and all other parts
Even during normal operation, everything must shut down safely. - Only one ON and one OFF position is allowed
🔒 The OFF position must be lockable. - Star-delta and other speed switches ❌ can’t act as main switches
- If a machine has several power lines, each one needs its own main switch
⚠️ These must stop safely, even if only one is turned off.
Protection Against Electric Shock
- Enclosures protect live parts so only trained people can open them
🧰 These covers need special tools or keys. - No need to turn off the main switch before opening if the cover gives full protection
- DIN EN 50274 and VDE 0660-514 explain how to protect direct contact
- If someone can open the enclosure while it’s live, it needs IP2X or IPXXB protection
🔌 That means fingers can’t touch dangerous parts. - Fault protection stops shocks from broken insulation
Use protective equipment from DIN IEC 60364-4-41 (VDE 0100-410).
Equipment Safety After Power Failures
- Machines must not start by themselves when power returns
❗ That could be dangerous. - Self-holding contactors help keep machines off after a failure
- For two-wire control systems, a three-wire relay can prevent auto-restart
🔄 Main switches with undervoltage release also stop sudden restarting.
Overcurrent Protection
- Machines need protection against too much current
🔥 This protects both people and the machine. - The main supply gets protected with a fuse or circuit breaker
- Circuit breakers are better because they:
- Disconnect all wires
- Act quickly
- Avoid “single-phasing” (where one motor line stays powered)
⚡ These make things safer and more reliable.
Motor Overload Protection
- Motors over 0.5 kW (kilowatts) need overload protection
🌀 This protects against heat and motor failure. - Motors that start and stop a lot need special protection
- Thermal sensors inside motors are very useful
❄️ These work well if cooling is limited. - Overload relays help when motors get stuck or overheated.
Fault Conditions and Control Safety
- If something breaks, it must not cause danger
💡 Smart design avoids serious problems. - The standard DIN EN ISO 13849-1 shows how to analyze risk
- Safety design follows PU059070012: Safety Technology for Machines and Systems
✍️ This helps choose the best protection for each situation.
Emergency Devices and Stop Functions
- Every machine that could hurt someone needs an emergency stop
⛔ This device cuts power fast. - The stop should use:
- Relays
- Contactors
- Undervoltage releases
- The machine can’t restart until it’s reset and restarted properly
Just resetting is not enough. - Emergency buttons must follow rules:
- Handle is red with yellow background
- Easily found and used fast
- Emergency stops always take top priority
- Must work in tough environments
- Each emergency stop must clearly show what area it controls
🚨 This avoids confusion during danger.
Emergency Operation Devices
- The standard DIN EN 60204-1 gives two types of emergency tools:
- Emergency-stop devices
- Stop dangerous actions fast
- Emergency-off devices
- Use when there’s risk of shock from live wires
- These cut power in dangerous places
⚠️ These devices are not optional. Machines must always be ready to protect.
Safety is not just a requirement. It’s the only way to build, operate, and trust machines in any industry.
My Diary - Leonardo Cardillo 