Quantcast Three-Phase Versus Single-Phase Reclosers

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recloser is designed to operate. Voltage ratings of automatic circuit reclosers range from 14.4
kV to 69 kV for oil reclosers and from 14.4 kV to 34.5 kV for vacuum reclosers (per ANSI
C37.60-1981). Units rated 14.4 kV may be applied at any system voltage from 2.4 - 14.4 kV, as
long as the proper interrupting ratings are used. Older units, that carry nominal voltage ratings
below 14.4 kV (i.e., 2.4 kV or 4.16 kV), may still be in service. Continuous Current Rating. The continuous current rating is the magnitude of rms
current in amperes that the recloser is designed to carry continuously. In many cases the
continuous current rating is limited by the series solenoid coil rating. As load current
requirements change, therefore, it is necessary to replace the solenoid coil with one having the
required rating. The continuous current ratings of automatic circuit reclosers range from 5 to
1120 A. Minimum Trip Current Rating. The minimum trip current rating is the minimum
current at which a recloser will operate. The pickup is adjustable, but generally a setting of 140
or 200 percent of the continuous current rating is used. The differential between minimum trip
and continuous current ratings normally provides sufficient margin for inrush current pickup after
an extended outage on a feeder circuit. Interrupting Current Rating. The interrupting current rating is the maximum rms
symmetrical current that a recloser is designed to interrupt under the standard operating duty,
circuit voltage, and specified circuit constants.
3.6.4 Three-Phase Versus Single-Phase Reclosers. Automatic oil circuit reclosers are
available in both single-phase and three-phase (Figure 3-15). The application of reclosers is
dependent upon the type of loads being served. Three-phase equipment should not be served by
a feeder using single-phase reclosers. Operation and lockout of one of the reclosers would
cause single-phase operation of the three-phase equipment and result in possible damage. A
three-phase recloser for such an application would disconnect all three phases regardless of
which phase is faulted.
3.6.5 Construction. An automatic circuit recloser is made up of five major components:
housing, bushings, mechanism, interrupter, and controls. Housing. A vacuum recloser may be housed in a pad-mounted metal enclosure.
These enclosures are easy to install, are tamperproof, and are neat in appearance. A tank is used
to house the interrupter and the tripping and closing coils of an oil-filled recloser. The tank is
usually made of steel and is rectangular for a three-phase recloser and cylindrical for a
single-phase unit. Typical single-phase automatic recloser construction is shown in Figure 3-16. Bushings. The bushings are the insulating structures including through-conductors
with provision for mounting on the top of the recloser.


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