Sensor Module Checkout - Emerson Rosemount 2151N Reference Manual

Rosemount 2151N
SENSOR MODULE
CHECKOUT
51
NOTE
Numbers in parentheses refer to item numbers in Figure 5-1.
The sensor module (8) is not field-repairable and must be
replaced if defective. If no visible defect such as a punctured
isolating diaphragm or loss of fill fluid is observed, check the
sensing module in the following manner:
1. Remove the electronics assembly (4) from the
transmitter per the steps outlined in Electrical
Housing Disassembly section. This will allow
access to the sensor module pins located at the top of
the sensor module.
Refer to Figure 5-3 for the following steps.
Diode Check
Using a digital multimeter with diode test functionality,
measure the voltage drop of the sensor diodes
between the following sensor module pins (the
positive (+) lead should be connected to the first
sensor module pin listed):
A. Pin #3 and Pin #5
(Should measure approximately 1.2 volts)
B. Pin #4 and Pin #3
(Should measure approximately 1.2 volts)
C. Pin #4 and Pin #5
(Should measure approximately 2.4 volts)
NOTE
Results obtained using the above procedure may vary
depending on the specific meter that is used for testing
(manufacturer, model, type, etc.). Please contact Rosemount
Nuclear with any questions regarding test procedure and/or
results.
Resistance Check
Using a low-voltage ohmmeter, check resistance
between the following sensor module pins:
A. Pin #1 and all other Pins
(All measurements should be >10 mega
ohms)
B. Pin #2 and Pin #5
(Should measure between 15 kilo ohms and
38 kilo ohms)
C. All Pins and the module housing
(All measurements between pins and module
housing should be >10 mega ohms)
Reference Manual
00809-0000-4851 Rev AD
December 2023
Maintenance & Troubleshooting