
Alarms and Events
Table 5: Possible Alarms
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 | Low DC | The UPS has been running on | If the UPS is programmed for | |
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 | shutdown (This | battery power because of a power | ||
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 | alarm is normal | outage or problems in the AC input. | restart when the power outage | |
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 | when the UPS | Battery voltage has dropped below | ends and AC input is again | |
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 | has run on | the shutdown setting, and the UPS | available. If the UPS is not | |
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 | battery for a | has shut down. If bypass is within | programmed for  | |
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 | long time) | tolerance, the unit will transfer to | can restart the UPS when the | |
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 | static bypass operation. If not, the | power outage ends by pressing | |
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 | unit will transfer to  | the green button inside the door. | |
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 | will not supply output voltage. | 
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 | Low DC | The UPS has been running on | If possible, restore AC input | |
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 | warning (This | battery power for a while because of | power to the UPS. If you cannot | |
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 | alarm is normal | a power outage or problems in the | do this, prepare for a possible Low | |
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 | when the UPS | AC input. Battery voltage has | DC shutdown by shutting down | |
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 | has run on | fallen to the warning alarm setting. | the loads (protected equipment) | |
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 | battery for a | If the APC BC300 Series is | connected to the UPS. | |
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 | while) | operating on battery, the unit’s | 
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 | status will not change, but battery | 
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 | voltage will eventually drop to the | 
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 | shutdown setting. At this point, the | 
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 | unit will shut down and sound a | 
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 | “Low DC shutdown” alarm. If the | 
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 | “Low DC warning” alarm occurs | 
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 | during a battery capacity test, the | 
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 | unit transfers back to normal | 
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 | operation. | 
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 | If the unit has not been running on | 
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 | battery power, call APC Technical | 
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 | Support. | 
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 | Mains freq. is | The utility (AC input) frequency is | Ask an electrician to make sure | |
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 | out of tolerance | out of tolerance. The unit transfers | that the correct input frequency is | |
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 | to battery operation. If utility | available to the UPS. The | |
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 | returns to a frequency within | electrician must correct any | |
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 | tolerance, the unit transfers back to | problems in input frequency. If | |
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 | normal operation. If not, the unit | input frequency is correct, call | |
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 | continues to run on battery until | APC Global Service. | |
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 | the “Low DC shutdown” alarm | 
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 | occurs. Then, if bypass is within | 
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 | tolerance, the unit transfers to | 
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 | bypass. If not, the unit transfers to | 
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 | output voltage. | 
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 | Mains is | The utility (AC line voltage) was | If possible, restore AC input | |
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 | moment. out of | momentarily too high or too low. | power to the UPS. If AC input is | |
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 | tolerance (This | The unit transfers to battery; if | available to the UPS, ask an | |
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 | alarm occurs | utility returns to a frequency | electrician to make sure that 1) | |
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 | during a power | within tolerance, the unit transfers | the correct input voltage is | |
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 | outage) | back to normal operation. | available to the UPS. 2) this | |
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 | voltage is within an acceptable | |
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 | UPS range | |
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| User Guide APC BC300 Series 40kW 208/450/480V UPS | 17 | |||
