Applicable Systems
MAGNA1
Symptoms
The Grundfos MAGNA1 pump displays alarm code 40, indicating undervoltage. The supply voltage to the pump is too low for normal operation.
Possible Causes
- Power supply voltage below the pump's rated minimum voltage
- Power cable undersized causing voltage drop under load
- Loose or corroded connection in the power supply circuit
- Power supply phase loss or severe voltage imbalance
Troubleshooting Steps
- Step 1: Verify supply voltage at pump terminals with multimeter
Voltage must be within the specified range printed on the pump nameplate - Step 2: Check all power cable connections for tightness and corrosion
Connections must be clean and torqued to specification - Step 3: Inspect power cable size against pump current rating
Cable cross-section must be adequate for the pump's full load current and cable length - Step 4: Verify all three phases are present and balanced (3-phase pumps)
All three phases must read within 2% of each other
How to Reset
To reset: 1) Restore the power supply to within the rated range. 2) The pump will auto-reset when voltage returns to normal. Caution: Operating under undervoltage can cause motor overheating and premature failure.
Frequently Asked Questions
- Q: What voltage triggers undervoltage alarm code 40 on MAGNA1?
The undervoltage threshold depends on the pump model's rated voltage. Typically, it triggers when voltage drops below 85% of the rated value. Check the specific model manual.
- Q: Can the pump run with code 40 active?
The pump may continue to run at reduced performance under undervoltage conditions, but prolonged operation will damage the motor. The alarm should be addressed promptly.
Source: Grundfos MAGNA1 Installation and Operating Instructions, Fault Finding Table, Document 6908923
Category: Pump