Switch OFF the main Input Rectifier switch ( Q1 ) and the Static Bypass Input switch ( Q5 ). Step 6: Open the external Battery DC Circuit Breaker .
If the UPS needs repairs that require it to be completely shut down, you must transfer the load to maintenance bypass without dropping the load.
A "fix" that involves power cycling the unit without following the correct sequence can cause a total output failure. Always ensure the Maintenance Bypass Switch (MBS) is available and rated for the full load current.
Turn off the external battery cabinet circuit breaker. The internal components are now isolated, while your critical load runs directly on unconditioned utility power. Preventive Maintenance Checklist
Liebert Hipulse D systems contain lethal voltages. Only qualified service personnel should perform internal troubleshooting or manual repairs. Always follow Lockout/Tagout (LOTO) procedures, verify the unit is de-energized, and allow capacitors to discharge before servicing [1, 2]. 1. Initial Troubleshooting & Status Check
Open the Maintenance Switch (Q3) only after the load is back on the inverter. Conclusion
Turn the mechanical maintenance bypass switch to the 'ON' or 'CLOSED' position. The load is now powered directly by raw utility power.
Turn the Q3 / MBS switch from the OFF position to the ON (Bypass) position. The utility line is now running in parallel with the static bypass line.
Post-repair verification and documentation
If the input power is stable, clear the fault by using the control panel menu to navigate to . Inverter Fault / Overload