Source characteristics

DOE-SPEC-3021-97

3.2 Source characteristics.

ATTENTION:

Enter the characteristics of the normal input source below. If the input may come from more than one source

(such as commercial power or standby generator), then enter the worst case parameters. Remember the

available short circuit current depends on the upstream protection circuits. The normal voltage and frequency

variations of most commercial power systems is 5% and 0.5% respectively.

A complete input source specification should also include any transients expected on the system. Two common

conditions are listed, but the responsible engineer must know the source to be used and then list any additional

conditions that might be expected. For further guidance on transients refer to IEEE C62.41.

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3.2.1

Normal input sources.

a. The normal source for the UPS system has the following characteristics:

NORMAL AC

STANDBY

SOURCE

GENERATOR

SOURCE

Voltage/Phase/Wire

No. of Input Sources

[Single/Dual]

Power Factor Lagging at

Nominal Input Voltage

Frequency

System Grounding Solid,

High Resistance, Ungrounded

Available Short-Circuit

Current (amperes rms sym.

at rated voltage for a bolted

three-phase fault)

Steady-State Voltage

Variations

% (+)

% (-)

Frequency Variations

% (+)

% (-)

b. Transient conditions which may be expected are:

! Motor starting transients causing voltage surges of [200]% with a duration

of [50] microseconds.