Buck-Boost
transformers are small, single phase, dry type distribution
transformers designed and shipped as insulating/isolating
transformers. They have a dual voltage primary and a dual voltage
secondary.
These transformers
can be connected for a wide range of voltage combinations. The most
common use is to buck (lower) or boost (raise) the supply voltage a
small amount, usually 5 to 27%. Buck-boost trans formers are in
compliance with NEC Article 210-9, Exception 1 when field connected
as
an
autotransformer.
However,
Buck-Boost transformers will not compensate for fluctuating line
voltages. They should only be used when line voltage is relatively
constant. Fluctuating line voltages should be regulated with a Line
Voltage Conditioner.
The advantages of
using a buck boost transformer over an equivalent standard isolation
transformer are as follows:
Advantages
1) Used in a
variety of applications
2) Inexpensive
3) Smaller and
lighter
4) More efficient
nameplate
5) 5-10 times
increase in KVA
Disadvantages
1) No circuit
isolation
2) Cannot create a
neutral
3) KVA and
voltages do not match what’s on the nameplate KVA and voltages
Buck-boost
transformers offer an economical solution to the adjustment of line
voltages that are slightly above or below normal. When a Buck-Boost
transformer is connected as an autotransformer, only a portion of the
load kVA is actually transformed. The majority of the load kVA is
passed directly through to the source.
For this reason a
Buck-Boost transformers may be used to supply a much larger load kVA
than is indicated on the nameplate.
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