Electrical System
Cabinet Maintenance
General Rules
- Only qualified electricians may open electrical cabinets
- Always disconnect main power and wait 5 minutes for DC bus discharge
- Use dry nitrogen or a vacuum with HEPA filter for cleaning — never use compressed air
- Keep cabinet doors closed while the machine is running
Inspection Checklist
| Item | Frequency | Criteria |
|---|---|---|
| Cabinet temperature | Weekly | < 45°C ambient inside cabinet |
| Filter mats | Weekly | Clean, not clogged |
| Cooling fan operation | Weekly | All fans spinning freely |
| Terminal block tightness | Monthly | Torque-check per manufacturer spec |
| Control voltage (24VDC) | Monthly | 23.5–25.0 VDC |
| Servo drive DC bus voltage | Monthly | Within ±5% of nominal |
| Backup battery voltage | Monthly | ≥ 3.0V (replace at 2.8V) |
| Relay/contactor contact wear | Quarterly | No pitting, no sticking |
| Main breaker mechanism | Yearly | Clean contacts, test mechanism |
| Ground resistance | Yearly | ≤ 4Ω |
| Megger test (motor windings) | Yearly | ≥ 5MΩ at 500V |
| Thermal imaging scan | Quarterly | No hotspot > 20°C above ambient |
Cable Management
| Cable Type | Inspection Frequency | Criteria |
|---|---|---|
| Drag chain / cable carrier | Weekly | No broken links, no chafed jackets |
| Motor power cables | Monthly | No discoloration at terminals |
| Encoder / feedback cables | Monthly | Shielding intact, connector tight |
| Heater band leads | Monthly | No brittle insulation, no arcing marks |
| Ground braids / straps | Quarterly | Secure at both ends, no corrosion |
UPS and Backup Power (if installed)
- Test UPS battery monthly (simulate power loss)
- Replace UPS battery every 3 years
- Record maximum load current during normal operation
Emergency Power-Off Verification
Test all emergency stop circuits monthly:
- Press each E-stop button — machine stops immediately
- Verify controller shows correct E-stop alarm
- Verify hydraulic pump motor stops / servo drive de-energizes
- Verify safety doors remain interlocked
- Reset and verify normal operation resumes
⚠️
Never reset an E-stop without identifying and correcting the condition that caused the stop. An E-stop event is a safety warning, not an inconvenience.