Ametek Drexelbrook Z-tron Level Control 502-302X Series Installation And Operating Instructions Manual page 26

502-302 Series Z-tron Level Control
X
5.2 Testing the
Sensing Element
(cont.)
___________________________________________________________________________________
d. The high sensitivity 402-302
measure non-conductive, granular material. If this is
the case, typical sensing element readings will be open
circuit (infinite ohms).
A new sensing element that is clean and not coated or
wet should read open circuit on all sensing element
connections.
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 sens-
ing element. In this case, the sensing element may be
dried until the resistance has disappeared.
If your process material is semi-conducting, you may
read some resistance between sensing element termi-
nals. The lowest permissable resistance values are:
Center wire to ground
Center wire to shield
Shield to ground
A resistance reading of less than 10 ohms on any sens-
ing element terminal is usually due to a metal-to-metal
short circuit. Check that the sensing element is not
touching any vessel structure.
Do not use the high sensitivity 402-302
water-base or conductive products.
22
Troubleshooting
Z-tron is usually used to
X
1000 ohms.
600 ohms.
300 ohms.
Z-tron on
X