Page 126 - Electromechanical Devices and Components Illustrated Sourcebook

88 Electromechanical Devices & Components Illustrated Sourcebook

Terminals
Mount Tabs
Cylindrical
Core
Frame
Rain Cap
Mount Collar
Adjustment Wiper
Shaft
Mount Nut

Case Knob

Figure 5-17 Commercial Variable Autotransformer

Conduit Connections
Figure 5-14 Commercial Voltage- These units are excellent pieces of equipment for a test bench
Matching Autotransformer or for temporary installations. They generally have a stan-
dard AC cord for the input and a fused AC receptacle for the
output. Some models are even supplied with output volt-
meters.
Variable autotransformers are also supplied in panel mount
versions, as shown in Figure 5-17. This arrangement makes
them particularly suitable for custom or OEM installations.

Three-Phase Transformers
Input
Transformers are also used with three-phase power. A three-
phase transformer is three, single-phase transformers that
share a common core. They can be wired to accept and to out-
put either Delta or Wye configurations (see Chapter 2).
Figures 5-18, 5-19, 5-20, and 5-21 show the four basic con-
Output
figurations for three-phase transformers.
Figure 5-15 Variable Commercial three-phase transformers have the same gen-
Autotransformer Schematic eral appearance as a single-phase unit, except that there are

Core
Secondary Coils
Primary Coils
Control Knob

Volts Scale

Cooling Vents Input (Delta) Output (Delta)

ON
Fuse Holder
Power Switch FUSE OFF

Output Receptacle OUTPUT
Base AC Cord
Figure 5-16 Packaged Commercial Variable Figure 5-18 Delta-Delta Configured Three-Phase Transformer
Autotransformer Schematic