Use a multimeter in diode mode to test the IGBT gates. If you find a short circuit between the Collector and Emitter, the IGBT module must be replaced.
), the UPS is operating as designed to protect your load. You must wait for the utility grid to stabilize.
: Always lock out/tag out (LOTO) upstream breakers and the battery main breaker before opening protective panels.
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Wear rated electrical safety gloves, eye protection, and arc-flash clothing. liebert hipulse d ups manual fix
Ensure there is at least 2 to 3 feet of clearance around the top and rear vents of the UPS cabinet to allow proper heat dissipation. Step 3: How to Safely Transfer to Maintenance Bypass
Working on industrial UPS systems like the Liebert HiPulse D involves lethal voltages and high-current energy storage systems.
Inspect for loose or corroded terminal connections.
To minimize manual emergency fixes, execute these maintenance tasks at regular intervals: Action Item Target Specification Inspect air filters and ventilation fans Clean or replace filters; check for smooth fan rotation Quarterly Record battery string voltages and ambient room temperature Standard room temp: 20°C–22°C Semi-Annually Use a multimeter in diode mode to test the IGBT gates
Physically reset the EPO button (usually a red mushroom button).
: Check input connections and incoming utility power. The unit will automatically switch to battery mode.
Measure the total DC bus voltage. If it is significantly lower than the nominal string voltage, look for individual dead or dropped cells within the battery racks.
This indicates a leakage current to the ground. Inspect the battery rack for leaking electrolyte or damaged insulation. Inverter and Output Faults You must wait for the utility grid to stabilize
Once the "fix" (e.g., cleaning, board replacement) is complete, follow the safe startup sequence: Close the Input Breaker (Q1). Wait for the rectifier to start and DC bus to stabilize. Close the Battery Breaker (Q4). Restart the Inverter from the Control Panel. Transfer load from Static Bypass back to Inverter.
The Hipulse D has a "Neutral Current Protection" feature. If the third harmonic content on the output exceeds 30% of the fundamental current, the software falsely detects a ground fault.
Reduce the connected load immediately. The UPS may transfer to bypass if the overload continues.