3. Select an ANSI Metering Accuracy Class in
accordance with the following Table:
Primary Amp Rating (of CT)
Accuracy Class
200
0.3 thru B-0.1
300-400
0.3 thru B-0.2
600-1200
0.3 thru B-0.5
1500
0.3 thru B-0.9
2000-3000
0.3 thru B-1.8
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Current transformers shall conform to IEEE C57.13. Provide current
transformers with a metering accuracy Class of 0.3 through [_____], with a
minimum RF of [_____] at 30 degrees C, with 600-volt insulations, and 10 kV
BIL. Provide butyl-molded, window-type current transformers mounted [on
the transformer low-voltage bushings. Route current transformer leads in a
location as remote as possible from the power transformer secondary cables
to permit current measurements to be taken with hook-on-ammeters.] [in the
current transformer cabinet.]
2.10.4.6
Voltage Transformers
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NOTE: See TM 5-811-1/AF AFJMAN 32-1080 for guidance
regarding voltage transformers. Minimum standard
potential transformer accuracies for metal-clad
switchgear are not listed in IEEE C37.20.2.
Accuracy classes as listed in IEEE C57.13 are 0.3,
0.6, and 1.2. Standard burdens for each accuracy
class are W, X, Y, ZZ, and M. The designer should
check the burdens connected to determine the actual
accuracy class and burden required. In general,
ANSI C12.11 requires 0.3 accuracy class for up to Y
burdens, except for voltages of 5 kV and below.
Where metering potential transformers are provided,
a 0.3 accuracy class should be specified, if
available for the voltage rating and burden needed.
**************************************************************************
Voltage transformers shall have indicated ratios. Units shall have an
accuracy class rating of [_____]. Voltage transformers shall be of the
drawout type having current-limiting fuses in both primary and secondary
circuits. Mechanical interlocks shall prevent removal of fuses, unless the
associated voltage transformer is in a drawout position. Voltage
transformer compartments shall have hinged doors.
2.10.5
Watthour Meters
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NOTE: Coordinate demand interval with local
utility. Coordinate devices with EMCS equipment.
For small, non-critical installations,
residential-type watthour meters may be adequate.
Revise paragraph as required.
**************************************************************************
Watthour meters shall conform to ANSI C12.10, except numbered terminal
wiring sequence and case size may be the manufacturer's standard. Watthour
SECTION 16375A
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