Introduction

UPS Model and Battery Configurations

There are two important considerations when selecting the UPS model and battery configuration to properly safeguard your equipment:

:The UPS output power rating (VA) should be specified according to the total power demand of the equipment to be protected. Some margin should be allowed for potential expansion of the protected system, and for possible inaccuracy in calculating or measuring the actual power requirement.

:The battery should be sized according to the desired backup time. The backup time is longer if the load is less than the nominal power rating of the UPS.

Load Requirements

Determine the total load requirements, in volt-amperes (VA), of the equipment to be protected by the UPS. The UPS load should not exceed the UPS rating. To determine the total load requirements:

1.Obtain the load ratings from either the nameplate or operator’s manual of the equipment to be protected by the UPS. The ratings are listed in either watts (W), amperes or amperes max (A), or volt-amperes.

2.If the rating is in watts, multiply by 1.4 to obtain the VA requirement (this is the typical relationship between watts and volt-ampere ratings in most computing equipment).

If the rating is in amperes or amperes max, multiply by the input voltage to obtain the VA requirement.

3.Add all of the resultant VA ratings together to obtain the total load requirements of the equipment to be protected (see Figure 2).

 

3 COMPUTERS

 

 

3 MONITORS

 

EXTERNAL

 

300 WATTS

 

 

2 AMPS

 

MODEM

 

 

 

 

 

 

EACH

 

 

EACH

 

50 VA

 

 

 

 

 

 

 

3 x 300 WATTS X 1.4 = 1260 VA

3 x 2 AMPS x 240V = 1440 VA

50 VA

1260 VA + 1440 VA + 50 VA = 2750 VA (Total Load Requirements)

Figure 2. Volt-Amperes Calculation Example

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Powerware® 9150 User’s Guide : www.powerware.com