APC MXA002 Datasheet download pdf (Page 32)

Operation on-battery is limited in duration according to available battery capacity and

load. Local users are alerted to this mode by visual and audible indicators. When on-

battery, the UPS displays available run time and emits a sequence of four beeps every

30 seconds. During an extended mains failure, the battery capacity will eventually

become too low to support the load and the UPS will shut down. The UPS alerts the

user to a low battery condition 2, 5, 7, or 10 minutes before shutdown, depending

upon the user setting. The UPS beeps once every second to warn local users of the

low battery condition. The UPS alerts remote users to on-battery operation and low

battery conditions using serial communications or simple signaling from the Computer

Interface port.

5.1.5 Bypass mode

When in bypass mode, the load is supplied power conditioned by the Isolation Unit.

However, the load is not protected from mains voltage sags, swells, or blackouts. The

UPS automatically transfers to bypass mode when a failure occurs in the Electronics

Unit, including blocked fan, battery charger fault, overtemperature, and welded main

relaysee Section 7.2 for a complete list of fault messages. The UPS also automati-

cally transfers to bypass if the EU separating screw is loosened. A manual bypass

switch on the EU is used when maintenance of the EU is required. The UPS must be

returned to on-line operation manually.

Local users are alerted to this mode by visual and audible indicators. When in bypass,

the UPS displays the reason for bypass (fan failure, EU switch actuated, etc.) and

beeps. The UPS alerts remote users to the bypass conditions via serial communica-

tions from the Computer Interface port.

5.1.6 Transfer between modes of operation

Transfer of load power to and from all modes of operation occurs synchronously with

the mains voltage phase. See the Specifications section of this manual for transfer time

ratings.

5.0 Operation

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APC MXA002 Datasheet Page 32