Ametek Thermox WDG-VRM, Руководство пользователя

Страница: 94 / 104

8-4 | Thermox WDG-V RM
Wiring Checks
interconnecting Wiring Problem
Make sure all wiring connections between the control unit
and the sensor are terminated to the proper locations and
are seated properly. This includes ensuring that sets of
wires are not reversed, and that the cable is not damaged
or melted.
Thermocouple Checks
open Thermocouple
Remove power to the control unit and the sensor. Measure
across terminals “+TC-” on the sensor board with an ohm
meter. If an open is measured, replace the thermocouple.
shorted/Failed Thermocouple
Check that the thermocouple leads are not shorted to
chassis ground by using an Ohm meter to measure
between terminal TC+ on the sensor board and chassis
ground, and between terminal TC- on the sensor board
and chassis ground. If shorted, replace the thermocouple.
To verify the operation of the thermocouple itself, remove
the thermocouple from the sensor and heat its ceramic tip
to a known temperature. Measure the millivolt output with
a proper temperature indicating meter (type K thermocou-
ple). If the thermocouple reads inaccurately, replace it.
reversed Thermocouple Wires
First, view the cell temperature via the Home screen or
Diagnostic screen. If the thermocouple leads are reversed,
the displayed temperature will be decreasing as the sensor
warms up (this will usually happen at start-up or after you
replace a thermocouple). This indicates that the thermo-
couple wiring is reversed. If you just replaced a thermo-
couple, check the leads from the thermocouple to the
sensor board: yellow wire connects to terminal TC (+), red
wire connects to terminal TC (-).