UEi Test Instruments DL235 - Manual (Page 6)

DL235-MAN P. 5
The resistance in the test leads can diminish accura cy on the lowest
(400-ohm) range. The error is usually 0.1 to 0.2 ohms for a standard pair
of test leads.
When measuring resistance, be sure that the contact between the probes
and the circuit under test is good. Dirt, oil, solder flux, or other foreign
matter seriously affect resistance.
Continuity Testing
Press the “
” push-button to enable the continuity testing mode,
This meter defaults in the 400-ohm range and then highest bar graph
scale shows 400. The digital display reads “OFL” (Fig 8).
Continuity testing verifies that circuit connections are intact. Test
resistances below 35Ω cause the meter to emit a continuous tone.
Table 1. Beeper Response in Continuity Test
The continuity mode is extremely fast and can be used to detect either
shorts or opens that last for as little as 100 milliseconds. When a change
is detected, the beeper tone is “stretched” to last at least 1/4 second,
so you can hear it and detect both shorts and opens.
This can be a valuable troubleshooting aid when looking for intermittent
associated with cables connections, switches, relays, etc. If the test
value is very close to the threshold, erratic beeps can also occur due to
environmental electrical noise (EMI).
Using Soft
Observe that “SOFT” is displayed after pressing the “SOFT CREST”
push-button once. This “SOFT” mode digitally displays a running
average of readings over 3-second interval to reduce the fluctuation of
the readings. The bar graph is unaffected by this “SOFT” function and
updates 20 times each second (Fig 9).
“SOFT” function can be used for ampere readings or voltage readings.
Press the “SOFT CREST” push-button twice when in the AC or DC
amperes mode, or once when in the voltage mode, in order to
exit “SOFT”.
Using Crest
Observe that “PEAK” is displayed after pressing the “SOFT CREST”
push-button twice. “PEAK” is available for AC ampere readings only
and can not be selected when in the other modes (Fig 10).
Both the digital display and bar graph measure the half-cycle peak AC
amperes when “PEAK” is display.
The crest factor of a waveform is the ratio of its half-cycle peak amperes
to its rms amperes.
Crest Factor =
The crest factor is a nominal 1.414 for linear current flow without current
wave distortion. Crest factors other than 1.414 indicate the presence of
harmonic current flow. (see 6.1 non-linear loads).
Press the “SOFT CREST” push-button once to exit “CREST”. Then,
“PEAK” is no longer displayed.
Enabling Record
To enable “RECORD”, press the “MIN/MAX” push-button. The
blinking “RECORD” is displayed. The recording of a new maximum is
indicated by beep sounds. We can use “RECORD” in all modes of this
meter, but we can not change meter modes while in “RECORD”, for
example, from voltage to amperes (Fig 11).
In the AC amperes mode, the bar graph displays the rms value of
current flow and also blinking pointers at the recorded MIN and MAX.
But, in the frequency mode, the bar graph displays the rms value of
current flow only. No blinking pointers.
In “SOFT”, the softened values of rms current flow, frequency or
voltage is recorded for MIN, MAX and AVG. The bar graph displays
instantaneous values of rms current with blinking pointers.
In “CREST” (that is, “PEAK”) mode, the half-cycle peak amperes are
recorded for MAX. In “CREST” mode, MIN and AVG are not available.
The bar graph displays a single blinking pointer for MAX. The
“CREST” (that is, “PEAK”) function is not available in the other
(V or Hz or Ω) modes.
Input Range
400Ω
Beeper On If
Approx. <35Ω
(Fig 7)
(Fig 8)
Half-Cycle Peak Amperes
RMS Amperes
(Fig 9)
(Fig 10)