UEi Test Instruments ALS1 - Manual (Page 2)

Introduction
Line splitter for clamp-on meters eliminates the need to split electrical
cords or open electrical boxes for current measurements on 120V lines.
Features include
• 1 to 1 and 10 to 1 internal coils for better resolution
• 15A max.
Operating Instructions
Theory of Operation
A magnetic field, proportional to the magnitude of current, surrounds
all current carrying conductors. In an AC circuit the magnetic field will
induce a current. In the jaws of a clamp-on current probe when the
jaws are closed around the conductor.
If both conductors of the circuit are enclosed by the jaws of the probe
the magnetic fields will cancel and no measurement is possible. Most
120V AC appliances use two conductor cords which make it difficult
to isolate a single conductor for measurement. The ALS1 provides
temporary separation of conductors to facilitate measurement
of current.
1. Plug the ALS1 into a grounded type 120V AC receptacle. If a
grounding type receptacle is not available, a 2 to 3 wire adapter
must be used. Maintain ground wire integrity to minimize the
possibility of electrical shock.
2. Plug the appliance line cord into the end of the ALS1 and turn
on the appliance.
3. Place the jaws of the clamp-on current probe through the X1
section of the ALS1. The current being drawn by the appliance
can then be read directly from the indicator of the clamp-
on probe.
4. If the magnitude of the reading obtained in step 3 is less than
one-tenth of the full scale range of the clamp-on current probe,
and difficult to read, place the jaws of the probe through the X10
section. The magnitude of the current drawn by the appliance will
be the reading on the current probe meter divided by ten.
Example: With the range switch of the clamp-on current probe
set to 6 amps, the meter indicates 5.4 amps, and the jaws of the
probe are through the X10 section of the ALS1. The actual current
is 0.54 amps (5.4 amps ÷ 10 = 0.54 amps, or 540mA).
Interpretation of Results
1. Most appliance manufacturers state the rating of an appliance on
the frame, or housing. The rating will be stated either in AMPERES
or WATTS.
2. If the rating is stated in AMPERES then this figure may be
compared with the reading on the clamp-on current probe. A
reading that is significantly LOWER that the manufacturer’s rating
may indicate low line voltage., corroded terminals, or some other
fault, which results in a higher resistance to current. A reading that
is significantly HIGHER than the manufacturer’s rating may indicate
high line voltage, or a partial short in the appliance, which results
in a lower resistance to current.
The line voltage may be easily checked by inserting the test probes
of an AC voltmeter into the VOLT CHECK input jacks on the ALS1.
3. If the appliance rating is stated in WATTS, then multiply the
reading in current (taken directly from the clamp-on probe) times
the line voltage. The product will be the power consumption
in watts.
Example: The clamp-on current probe indicates that 8.5 amperes
is being drawn by the appliance. The line voltage is measured
and found to be 102V AC. The power consumption is 867 watts
(8.5 amps x 102 volts = 867 watts).
A power consumption which is significantly higher, or lower, than
the rated power consumption may be due to the factors given in
section 2, for low or high current readings.
ALS1-MAN P. 1