Com-Power CLA-050 - Manual

Absorbing Clamps
Features
Frequency Range - 30 - 1000 MHz
Test to CISPR 14 (EN 55014) requirements
Individual Calibration
Two Year Warranty
Description
The CLA-050 and CL-150 absorbing clamps meet the
CISPR 14 (EN 55014) section 6.11 requirement for
measuring radio frequency power generated and fed to
the EUT supply cable of household appliances, electri-
cal tools and similar apparatus.
The absorbing clamp consists of a calibrated ferrite
current transformer operating in the frequency range
of 30-1000 MHz and two groups of ferrite rings. The
ferrite rings acts as absorbers of energy and stabilizes
impedance. One set of ferrite rings surrounds the lead
from the transformer to the EMI meter to minimize
standing waves. The second group of ferrite rings
surround supply cable from the equipment under test.
These rings act as an absorber of energy and an im-
pedance stabilizer to isolate the equipment under test
from the mains. These rings are made up of two halves.
Therefore, the supply cable from the EUT can be placed
inside the aperture of the rings.
Two absorbing clamp models are available to accom-
modate the varying sizes of supply cables. The model
CLA-050 can accommodate supply cable up to 10 mm
(0.39 inches) in diameter and model CLA-150 can ac-
cept cables up to 32 mm (1.26 inches) diameter.
All absorbing clamps are individually calibrated before
shipment. The insertion loss and correction factors will
be supplied with each clamp.
Application
Use of an absorbing clamp is a practical alternative to
measurement of direct field strength from EUT supply
cables.
During the test, the equipment under test is placed on
a nonconductive table at least 40 cm from the nearest
reflecting object. The EUT mains conductor is placed
horizontally in a straight line for a distance sufficient
to permit movement of the absorbing clamp to obtain
the highest readings. The mains conductor is placed in
the clamp surrounded by absorbing rings and the cur-
rent transformer.
The standard requires the measuring instrument having
a 50 Ohm input impedance. The power (P) measured
using a 50 Ohm load is equal to the square of the volt-
age measured divided by 50. This can be expressed in
decibels (dB):
P = Power
10 log P = 10 log V2/50 = 20 log V-10 log 50
10 log P = 20 log V - 10 log 50
IL = Insertion loss
Corrected reading: 10 log P = 20 log V - 17 dB + IL
The numerical value of P (power) expressed in dB
(picowatts accross 50 Ohms) is found by substracting
17 dB from the numerical value of V in dB.
Com-Power Corporation (949) 587 - 9800 www. com-power.com [email protected]
CLA-050, CLA-150