WAYS TO PROTECT CNC MACHINE – Reasons & Solution
CNC stands for computer numerical control — the automated control of machining instruments like drills, lathes, mills, and 3D printers using a computer. The primary function of CNC machines — precise and automatic motion control — makes this sophisticated machine so popular.
Failures in CNC machines happen due to two important disturbances in low voltage networks: steady state errors (over voltage lasting several cycles, harmonics, RFI/EMI effects) and transient errors (transient over voltages due to lightning surges and switching surges from welding, capacitor bank switching, etc.).
The more common problem encountered in normal plant life is corruption of EPROM (Erasable Programmable Read Only Memory), visible from sudden junk data appearing in the MMI (Man Machine Interface) panel. During a surge, a sudden high voltage appears in the pins of the IC, causing it to believe it is in programming mode — this is the cause of EPROM corruption.
Common Myths About Existing Protection
- External Lightning Protection — for protecting the building from direct lightning strike only, not equipment surges
- MCB/MCCB — for protecting against short circuit due to power frequency fault currents; they operate in milliseconds, by which time surges have already passed through
- Earthing — for personnel safety and equipment safety, not transient surge protection
- Shielding — to protect equipment from RFI/EMI effects only
- Isolation Transformer — mainly to protect equipment from faults on the primary side
- UPS — to provide continuous power through battery in case of mains power failure
- Intrinsically Safe Barriers — to restrict electrical energy in hazardous areas
Hence SPDs — Surge Protection Devices — are the only protectors for CNC machines against transient surges. Depending on the incoming supply (3-phase with or without neutral), SPDs with potential-free contact and thermal disconnector shall be installed between Phase to Neutral and Neutral to Protective Earth. Requirement class is Class I+II as per IEC 61643-11.
This is the first level of defence. For MMI having 24V DC power supply or PLC with DI/DO, suitable additional SPDs need to be selected. Please contact us for a holistic solution which will ensure decades of trouble-free operation of all your sensitive electronic equipment.
Please let us know if you need further assistance or have any requirements: [email protected]
