Page 154 - Uninterruptible Power Supplies

Static Uninterruptible Power Supplies
152 Chapter Five

200

V L
150

W L
Percent 100

I L

50

0
0 10 20
Minutes
Typical Lamp Start Condition
Sodium Discharge Lamp.
V L = Lamp Voltage
W = Lamp Wattage
L
I L = Lamp Current
= Lamp Lumin Average
Figure 5.11

high starting surge, depending on the type of lamp between 15 to 20
times normal run current decaying to normal load current within 20 to
100 ms. Discharge lamps have unusual starting conditions (see Fig. 5.11).
O represents light output, IL lamp current, W1 lamp wattage, and V1
lamp voltage. These figures are lamp figures, lamp control gear present
the incoming supply with approximately two times full load current,
decaying within 10 min for sodium lamps. These figures of starting time
vary with lamp type.
Motor loads can present the power supply with a wide variety of
starting surges, for example, squirrel cage motors giving 7 to 10 FLC
with a time span for decay to FLC being anywhere between 1 to 10 s.

Typical Specification
As a guideline a modern UPS output will provide the following perfor-
mance figures:

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