Reference Manual
Table Of Contents
- Rosemount 1408H Level Transmitter
- Contents
- 1 Introduction
- 2 Transmitter overview
- 3 Mechanical installation
- 3.1 Safety messages
- 3.2 Installation considerations
- 3.3 Mounting preparations
- 3.4 Mount transmitter on tank
- 4 Electrical installation
- 5 Configuration
- 6 Operation and maintenance
- 7 Service and troubleshooting
- 7.1 Safety messages
- 7.2 Diagnostic messages
- 7.2.1 Device hardware fault – Device exchange
- 7.2.2 General power supply fault – Check availability
- 7.2.3 Device software fault – Check firmware revision
- 7.2.4 Parameter error – Check data sheet and values
- 7.2.5 Short circuit – Check installation
- 7.2.6 Device memory failure – Restore default settings
- 7.2.7 Level measurement lost – Check application
- 7.2.8 Simulation active – Check operational mode
- 7.2.9 Device temperature over-run – Clear source of heat
- 7.2.10 Device temperature under-run – Insulate device
- 7.2.11 Primary supply voltage over-run – Check tolerance
- 7.2.12 Primary supply voltage under-run – Check tolerance
- 7.2.13 Maintenance required - Cleaning
- 7.3 Troubleshooting incorrect level readings
- 7.3.1 Reported level is too high or low
- 7.3.2 Level is stuck in measuring range
- 7.3.3 Level is stuck in full tank
- 7.3.4 Level value drops when close to antenna
- 7.3.5 Measured level fluctuates
- 7.3.6 Measured level is occasionally unstable
- 7.3.7 Lagging of measured level
- 7.3.8 Incorrect level at 100% (20 mA)
- 7.3.9 Incorrect level when product surface is above 50%
- 7.3.10 Dropping of level close to tank bottom
- 7.3.11 Level measurement is lost in an empty tank
- 7.3.12 Alarm mode close to tank bottom
- 7.4 Managing disturbance echoes
- 7.5 Service and troubleshooting tools
- 7.6 Service support
- A Specifications and reference data
- A.1 Performance specifications
- A.2 Functional specifications
- A.3 Physical specifications
- A.4 Dimensional drawings
- B Product certifications
- C Configuration parameters
7.3.4 Level value drops when close to antenna
Level value drops to a lower value when product surface is close to antenna.
Figure 7-4: Symptom
A
B
C
D
A. Level
B. Time
C.
Actual level
D. Reported level
Possible cause
Product surface is within the Upper Null Zone and a disturbance echo is interpreted as the
product surface.
Recommended actions
• Check the setting of the Upper Null Zone.
Related information
Change the upper null zone
Reference Manual Service and troubleshooting
00809-0100-4480 September 2020
Reference Manual 55