P-5000 Precision Current
This transformer is very 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 of the P-5000 transformer
make it well suited as a standard for calibrating work. Because of the particular current
ranges provided by this transformer (from 5 amperes to 5000 amperes), the P-5000 is
especially well suited for testing current transformers for ratio errors and phase angle
with the Knopp Transformer Comparator.
The range of a 5 ampere meter or wattmeter can be
accurately extended by this transformer to cover all current values between 5 amperes and
5000 amperes, with the advantage that the ammeter need not be used below the half-scale
The Knopp Precision Multirange Transformers have
excellent ratio and phase angle performance, both inter-range and overall. The P-5000
transformer is furnished for a specified secondary burden, which can be any value between
0 and 25 volt-amperes. With a secondary burden of 15 volt-amperes, to give an example, the
ratio of this transformer at 100% of full load current is well within .02% and the phase
angle is within 1 minute, and at 10% of full load current the performance is within .04%
and 2 minutes.
A total of 30 primary ranges are provided. The
self-contained primary ranges are: 5, 10, 15, 20, 25, 50, 75, and 100 amperes, and the
following primary ranges can be obtained with an inserted primary of 1 primary turn: 5000,
4000, 3000, 2500, 2000, 1500, 1200; 2 turns: 1250, 1000, 750, 600; 3 turns: 500, 400; 4
turns: 625, 375, 300; 5 turns: 800, 240; 6 turns: 250, 200; 8 turns: 150; and 12 turns:
125 amperes. The secondary is 5 amperes.
The transformer housing insulates the inserted
primary from the transformer windings for 2500 volt circuits. The wound primary is for use
on 250 volt circuits.
The transformer can be calibrated in itself by the
Knopp One-to-One method, by direct comparison of the primary current against the secondary
The Type P-5000 Knopp Precision Multirange
Transformer weighs 32.5 lbs.; and the bakelite case, which is fitted with a leather
handle, measures 11.5" wide, 4.5" deep, and 13.875" high. The center
opening is 4" in diameter. The secondary is provided with a convenient