UNI-T UT305A, User Manual, Page: 17 / 26

17
HOLD
The display will remain activated 8 seconds after the
trigger is released. HOLD appears in the upper middle
of the display. When the trigger is pulled again, the
Thermometer will begin measuring in the last function
selected.
Typical Measurements
This section describes a variety of measurements often
performed by technicians.
Reminder :
l
User could select to turn on or off the backlight
and laser whenever you are making readings with
the Thermometer. But if you are using USB to
power up the Thermometer, the two levels white
colour backlight will be on automatically.
l
Relatively high emissivity normally means emissivity
setting of about 0.95.
l
Relatively low emissivity normally means emissivity
setting of about 0.30.
l
When user cannot identify the emissivity of the
object to be measured, user could cover the surface
to be measured (temperature >150 ) with black
electric tape (emissivity of about 0.95). Allow time
for the tape to reach the same temperature as the
object to be measured. Measure and record the
temperature of the tape.
Target the Thermometer to the object to be measured,
adjust the emissivity setting to make it as the same
temperature as the tape. At this time, the Thermometer
emissivity setting is close to the emissivity of the
object to be measured, measurement could be started.
Testing Contactors (Starters)
1. Press SET to select emissivity. Press / to select
relatively low emissivity for bright contacts, or 0.7 mid
level for darkened contacts.
2. Press
YELLOW button to select MAX.
3. Measure line and load side of one pole without
releasing trigger
4. A temperature difference between the line and load
sides of a pole indicate increased resistance of one
point and a contactor may be failing.