P-2000-2 Precision Current
The Type P-2000-2 Knopp Precision Current
Transformer is useful for high and low voltage work in the laboratory, shop, and field,
for testing, measuring, and calibrating. The excellent accuracy and the One-to-One
calibrating feature make it well suited as a standard for calibrating work. The range of a
5 ampere watthour meter standard or a 5 ampere ammeter or wattmeter can be accurately
extended by this transformer to cover all current values between 75 amperes and 2000
amperes, with the advantage that the secondary instrument need not be used below the
three-quarter load or scale point.
Because this through-type current transformer
provides ranges above 100 amperes, it is a useful transformer as a complement to the
self-contained Type RA, RB, and RC Knopp Precision Transformers which are limited to a
maximum of 200, 100, and 400 amperes, respectively.
A noteworthy feature of Knopp Precision Multirange
Transformers is the excellent ratio and phase angle performance, both inter-range and
overall. The P-2000-2 is compensated for a specified secondary burden which can be any
value between 0 and 20 volt-amperes. When used with the burden for which compensated, the
accuracy on all ranges is well within .02% for ratio and within 1 minute for phase angle
from 20% to 150% of full load current. At 10% of full load current, the ratio is within
-.05% and the phase angle is within 3 minutes leading.
A total of 17 through-type primary ranges are
provided as follows: 100 and 120 (10 primary turns), 125 and 150 (8 turns), 200 (5 turns),
250 and 300 (4 turns), 400 (3 turns), 500, 600, 750, and 800 (2 turns), and 1000, 1200,
1500, 1600, and 2000 (1 turn). The secondary is 5 amperes.
The transformer housing insulates the inserted
primary turns from the transformer secondary winding for 2500 volt circuits.
The transformer can be calibrated in itself using
the Knopp One-to-One method, by direct comparison of the primary current against the
secondary current of the 200-turn secondary. For this test, the winding from the 200-turn
point to the 400-turn point is used as the primary.
The P-2000-2 is of the ring-core, toroidally-wound
type. Net weight is approximately 25 lbs. The black phenolic case measures 8.75"
wide, 4" deep, and 11" high, including binding posts. Window diameter is
3". The secondary is provided with a convenient short-circuiting switch.