Power Supply & Electrical Connections
Electrical Specifications
Standard Power Requirements
| Parameter | Specification |
|---|---|
| Voltage | AC 380V ± 10% (3-phase, 4-wire + ground) |
| Frequency | 50 Hz ± 1% |
| Voltage imbalance | ≤ 3% between phases |
| Ground resistance | ≤ 4Ω |
| Overcurrent protection | Per machine nameplate (main breaker sizing) |
⚠️
Voltage imbalance is one of the most common causes of servo drive failure. A 3% imbalance at the mains can result in 15–20% current imbalance in the drive, causing premature capacitor and IGBT failure. Check all three phase-to-phase voltages under load.
Cable Sizing
| Machine Tonnage | Recommended Cable (Cu) | Main Breaker |
|---|---|---|
| ≤ 1000 kN | 4× 25 mm² + ground 16 mm² | 63–100 A |
| 1000–3000 kN | 4× 50 mm² + ground 25 mm² | 125–200 A |
| 3000–6000 kN | 4× 95 mm² + ground 50 mm² | 250–400 A |
| > 6000 kN | Per engineering design | Per engineering design |
Recommended Power Distribution
Factory Main Breaker → Dedicated Transformer → Machine Breaker → MachineA dedicated transformer (D-Y or D-D configuration) is strongly recommended to:
- Isolate the machine from other factory loads
- Provide a stable neutral reference
- Reduce electrical noise from welding equipment, large motors, etc.
- Allow adjustment of voltage if factory supply is outside the ±10% tolerance
Connection Procedure
Main Power Connection
- Verify the main breaker is OFF and locked out.
- Open the machine electrical cabinet.
- Route the main power cable through the designated cable entry (bottom of cabinet).
- Connect the cable to the main breaker terminals:
- L1, L2, L3 to breaker input
- Neutral (if required) to neutral bus bar
- Ground to ground bus bar
- Verify phase sequence matches the machine label.
- Torque all terminals to the values specified on the breaker or bus bar label.
- Close cabinet and secure.
Grounding
The ground system is critical for safety and machine reliability:
- Install a dedicated grounding rod at the machine location if the factory ground resistance exceeds 4Ω.
- Connect the machine ground bus bar to the grounding rod with a minimum 25 mm² copper wire.
- Bond all machine panels, doors, and the controller cabinet together with ground braids.
- Verify ground continuity from the furthest point (e.g., operator panel) to the ground rod.
Control Transformer Check
- Measure secondary voltage of the control transformer.
- 24 VDC power supply output: 23.5–25.0 VDC at no load.
- Verify the controller powers on and starts correctly.
Post-Connection Checks
| Check | Criteria |
|---|---|
| Phase-to-phase voltage (L1-L2, L2-L3, L3-L1) | 380V ± 10%, imbalance ≤ 3% |
| Phase-to-neutral voltage (if applicable) | 220V ± 10% |
| Phase-to-ground voltage | ~ 220V (if neutral grounded at transformer) |
| Ground resistance | ≤ 4Ω |
| Phase sequence | Clockwise rotation (match pump motor direction) |
| Cabinet fan voltage | Matches fan rating (typically 220VAC or 24VDC) |