502-3000 Series Ztron
TM
Point Level Control
Specifications
28
5.3 Testing the
Sensing Element
NOTE
The sensing element is intrinsically safe. There-
fore, when using this product, it is recommended
that all service activity comply with appropriate
guidelines.
The following procedure is used to test the sensing element:
a.
Remove all wires leading from the sensing element to the
electronic unit.
b.
Remove spark protector if present.
c.
Use an analog ohmmeter
1
that is set to the R x 1K
ohm scale. Measure the resistances between each
pair of sensing element terminals. See Figure 5-1.
Center wire to ground
__________ohms
Center wire to shield
__________ohms
Shield to ground
__________ohms
d.
A new sensing element that is clean and not coated or
wet should look like an open circuit on all sensing
element tests.
e.
If the sensing element is clean and dry, and shows
resistance between terminals of less than 10K ohms, it is
possible that moisture has soaked into the packing gland
of the sensing element. In this case, the sensing element
may need to be be dried until the resistance increases to
its maximum value.
____________________________________
1
An analog ohmeter has a lower ohms/volt rating and provides more current to
measure the resistance than a digital ohmeter.
