CNC Shield · Power Secure Shield
Lightning and surge protection for your CNC machine
The Power Secure Shield from CNC Shield is a power protection panel for your machine against lightning strikes, brownouts, over and under voltage and phase disturbance, which cause downtime and damaged electrical parts.
Made in Germany.

Save your money and your machine
You spent a fortune on your CNC machines. Don't add the cost of repairing them after a lightning strike, a brownout, over or under voltage or a phase disturbance.
Surges from lightning strikes or switching can damage your equipment, and a loss of production from under voltage or phase loss can endanger the company. Prevention is better than repair.
What the Shield does
- Monitors the three-phase supply of the machine: phase sequence, phase rotation, phase balance, over and under voltage.
- Protects the machine's low-voltage installation against switching and lightning over voltages, with a surge arrester rated for lightning protection up to 100 kA.
- Protects motors against phase asymmetry and phase failure.
- Signals errors on the cabinet door, with potential-free switch contacts for a phase or surge alarm.
- Basic and Professional both include the emergency stop connection. The protection relies on it: connect the Shield to the machine's emergency stop, with a maintained ground.
- Connected correctly to the machine's emergency stop circuit, the Shield alarms the machine and puts it into e-stop as soon as it detects a power fault. That protects the machine's three-phase components — spindles, motors, pumps, power supplies and control supplies — from damage.

Read it at a glance
- System Ready
- No error: the system works properly.
- Phase Error
- Phase monitoring has released.
- Surge Error
- Lightning protection has released.
- Reset
- Resets the alarm.
Danger, high voltage inside: service by qualified personnel only.
Two levels: Basic and Professional
Both levels protect and monitor. Professional adds a display with metering, recording, alarming and a network connection.
| Function | Basic | Professional |
|---|---|---|
| Monitoring of three-phase mains for phase sequence | Included | Included |
| Phase rotation monitoring | Included | Included |
| Over and under voltage | Included | Included |
| Phase balance | Included | Included |
| Lightning protection 100 kA | Included | Included |
| Over voltage protection max 264 V | Included | Included |
| Lightning current | Included | Included |
| Surge arrester | Included | Included |
| Graphic LCD display | Not included | Included |
| Multiple languages | Not included | Included |
| Basic metering: voltage, currents, power (kW, kVA), frequency | Not included | Included |
| Min. / max. values | Not included | Included |
| Basic value memory | Not included | 200 |
| Measurement accuracy | Not included | ±0.2 % (voltage, current) |
| Sampling rate 170 samples per cycle at 60 Hz | Not included | Included |
| Set point monitoring | Not included | Included |
| Simple logic functions for alarming | Not included | Included |
| Phase unbalance | Not included | Included |
| Ethernet communication, Modbus TCP | Not included | Included |
| 40-day memory | Not included | Included |
| Real-time clock and calendar | Not included | Included |
| Cost allocation / energy monitoring | Not included | Included |
Professional uses a Siemens SENTRON PAC4200 meter for display and recording.
Standard sizes and custom builds
| Size | Max. current | Max. wire size |
|---|---|---|
| Power Secure Shield 35 | 150 A | 16–35 mm² |
| Power Secure Shield 95 | 230 A | 25–95 mm² |
| Power Secure Shield 120 | 300 A | 35–150 mm² |
Need a different current rating or wire size? We build custom sizes to your machine and supply.
Built for your supply voltage, for example 208 V or 400 V. Tell us your supply voltage and the machine, and we size the Shield for it.

Protect your machine
Tell us the machine, its supply voltage and the current it draws, and we quote the right size and level.