ANSI Standard Burden Sets
Testing and calibrating instrument transformers
often requires standard burdens of reliable accuracy and stability, and burdens that are
immune to stray fields and harmonics. The burden sets described in this leaflet have been
carefully designed to meet these requirements. They provide the standard burdens required
for the testing of current and voltage transformers for metering service, and for the
testing (within the current rating provided by the sets) of current transformers for
relaying applications, all as called for by ANSI/IEEE C57.13-1978.
One burden set, the Type BSC-5, provides in one unit
three of the ANSI standard burdens for current transformers for metering service, i.e.,
B-0.1, B-0.2, and B-0.5. The BSC-24 set includes B-0.9 and B-1.8, while the BSC-25
includes all metering burdens (B-0.1 through B-1.8). The heavier burdens are provided by
two sets. The Type BSC-8 covers the ANSI burdens B-1, B-2, and B-4 for current
transformers for relaying applications; the Type BSC-9A includes the ANSI B-4 and B-8
burdens. In addition we offer in one unit, the BSC-10, all burdens from B-0.1 through B-2.
The standard burdens for voltage transformers (120
volt secondaries) are covered by three sets. Three of the burdens, i.e., W, X, and Y, are
combined in one unit, the Type BSP-6 burden set. The burdens in this set are independent
of each other, each with its own pair of binding posts. The standard burden Z is supplied
in a separate unit, the Type BSP-7. Two of these BSP-7 burden sets can be used in parallel
to obtain ANSI burden ZZ. The ANSI M burden is contained in the BSP-20 unit.
These burden sets are of the portable type, supplied
in beige finished metal housings with engraved bakelite terminal boards. Extensive design
and development work in perfecting these burden sets, and the quality material and
skillful workmanship employed assure excellent performance and quality throughout. Details
pertaining to the accuracy and performance, as well as other specifications, are given
Accuracy: Resistance and inductance within 1.0%.
Stability: Variation with current of the 60 Hz.
impedance and power factor of the current transformer burdens does not exceed 2.0% in the
range from 0.5 to 10 amperes, and the variation does not exceed 1.0% from 1 to 10 amperes,
and 0.5% from 2.5 to 10 amperes. Variation of either inductance or resistance of the
voltage transformer burdens operated at 60 Hz. does not exceed 0.2% from 100 to 140 volts.
These data include the effects of self heating in an ambient temperature ranging from 60
degrees F. to 80 degrees F.
Shielding: The maximum leakage field four inches
from the cases of the burden sets operated at rated current or voltage is less than 0.5
oersted. Stray 60 Hz. magnetic fields of 100 oersteds changes the rated current of the
voltage transformer burdens less than 0.25% and the rated voltage drop of the current
transformer burdens less than 0.1%.
Harmonics: The percent harmonics in the voltage drop
of the current transformer burdens is less than 1.0% throughout the range up to 10
amperes. The percent harmonic current taken by the voltage transformer burdens is
approximately 0.2% at 80 volts, 0.3% at 120 volts, and 0.6% at 160 volts.
Dimensions: See below.
Weights: See below.