Engineering guide
Delta Ultron HPH alarm messages explained
The Delta Ultron HPH 60 to 120 kVA shows its alarms as plain messages on the LCD, such as OVERLOAD or BATTERY LOW SHUTDOWN. Chapter 11 of Delta's HPH user manual gives the possible cause and solution for each. A handful have an operator fix: reduce the load below 95%, improve ventilation, or reset a frozen LCD. Most say to contact service personnel, and the manual adds that an alarm which persists once causes are ruled out goes to the dealer or customer service.
Key facts
- OVERLOAD: remove unnecessary loads to bring the total load capacity below 95%
- BATTERY LOW SHUTDOWN: battery voltage is low; charge the batteries
- LCD error or no response: press UP and DOWN together for around 5 seconds to reset the LCD
- Persistent alarm: contact the local dealer or customer service
How the HPH reports alarms
The message appears on the LCD, and the manual's troubleshooting table pairs each message with a cause and a solution. Record the exact message and the time before anything is reset.
Load messages
| Message on the display | What the manual says | What to do |
|---|---|---|
| OVERLOAD | The UPS is overloaded. | Remove unnecessary loads to bring the total below 95%. |
| INDUSTRY PROTECT | In industrial mode, the output has an overcurrent. | Check that the output and the loads are normal. |
| SHORT CIRCUIT | The output has a short circuit. | Call service personnel. |
Delta asks for the total load to come back below 95% of capacity, not just under 100%, so leave a margin when you shed.
Temperature and fan messages
| Message on the display | What the manual says | What to do |
|---|---|---|
| OVER TEMPERATURE | The UPS temperature is too high. | Improve ventilation, reduce load, check from outside that fans run; filter cleaning is maintenance work. |
| PFC AMBIENT OVER TEMP. FAIL | The UPS temperature is too high (PFC ambient). | Same checks as OVER TEMPERATURE. |
| FAN FAIL | Fans are damaged or stuck. | Call service personnel. |
Supply, battery and display messages
| Message on the display | What the manual says | What to do |
|---|---|---|
| INPUT PHASE SEQUENCE FAIL | Input phase sequence is wrong. | Have an electrician check the input phase sequence. |
| BYPASS PHASE SEQUENCE FAIL | Bypass phase sequence is wrong. | Have an electrician check the bypass phase sequence. |
| BATTERY REVERSED | Batteries are connected in reverse. | Do not restart; have the battery polarity checked. |
| BATTERY LOW SHUTDOWN | Battery voltage is low. | Let the batteries charge once mains power is back. |
| LCD error or no response | LCD fail, communication fail or noise interference. | Press UP and DOWN together for about 5 seconds to reset the LCD; call service if it persists. |
Internal faults that need a technician
| Message on the display | What the manual says | What to do |
|---|---|---|
| INVERTER FAIL | Inverter is damaged. | Call service personnel. |
| OUTPUT FUSE FAIL | Output fuse is broken. | Call service personnel. |
| INPUT FUSE FAIL | Input fuse is broken. | Call service personnel. |
| AUX POWER FAIL | Auxiliary power is damaged. | Call service personnel. |
| BYPASS SCR SHORT FAIL | Bypass SCR driver damaged or SCR shorted. | Call service personnel. |
| INVERTER SOFT START FAIL | Inverter detection abnormal or driver damaged. | Call service personnel. |
| INNER COMMUNICATION FAIL | Inner communication cable not well connected. | Call service personnel. |
| DC BUS HIGH SHUTDOWN | Output abnormality or internal fault. | Call service personnel. |
Fuses, SCRs, the inverter and internal cabling are all inside the cabinet, so these are service calls. Our Delta Ultron service visits start from the alarm record, and when the external batteries are the cause, battery string replacement is planned around the load.
Related pages
Common questions
What does OVERLOAD mean on a Delta HPH?
The UPS is overloaded. Remove unnecessary loads until the total is below 95% of capacity.
How do I reset a frozen HPH display?
Press the UP and DOWN keys together for about 5 seconds. If the error remains, call service personnel.
What does INDUSTRY PROTECT mean?
In industrial mode, the output has an overcurrent. Check that the output and loads are normal.
What should I do on BATTERY REVERSED?
The batteries are connected in reverse. Do not restart; have the polarity checked.
What if an HPH alarm stays after all checks?
The manual says to contact the local dealer or customer service once all possible causes are eliminated.
Sources, checked October 4, 2026:
- Delta Ultron HPH Series, Three Phase 60/80/100/120 kVA, User Manual (501322640406), Chapter 11 Troubleshooting, pp. 72, 71-72
Send us the details
Fill this in and your own mail client opens with everything already written out. Nothing is sent from this site.
Brand names are trademarks of their owners and are used only to identify the equipment we service. We are not the manufacturer and are not affiliated with it.