Overview of Current Simulation Function
Current simulation is an important commissioning and diagnostic function of Endress+Hauser flow instruments (such as Promag 50, T-mass 65, Prowirl 72/73, Promass 80, and Prosonic 92). It allows the instrument to output a fixed 4-20 mA current signal, which is used to verify whether the wiring and configuration of the entire measurement loop (including cables, receiving devices, and control systems) are correct.
Through current simulation, engineering technicians can quickly locate fault points without relying on actual flow. The following video demonstrates a typical operating procedure:
Applicable Instrument Models
This guide applies to the following Endress+Hauser flow instrument series:
- Promag 50: Electromagnetic flowmeter
- T-mass 65: Thermal mass flowmeter
- Prowirl 72 / 73: Vortex flowmeter
- Promass 80: Coriolis mass flowmeter
- Prosonic 92: Ultrasonic flowmeter
The current simulation operation menu structures of these instruments are similar, but the specific paths may differ slightly depending on the model and software version.
Operating Steps
The following is a general current simulation operation procedure. Please adjust it according to the actual instrument model and site conditions.
- Enter the setup menu: Through the instrument local display or handheld operator, enter the "Setup" or "Diagnostics" menu.
- Select current simulation: Find the "Current output" or "Simulation" submenu and select the "Current simulation" function.
- Set the simulation value: Enter the target current value (such as 4 mA, 12 mA, 20 mA), or select a percentage (0%, 50%, 100%).
- Start simulation: After confirmation, the instrument will output the selected fixed current, and the actual flow signal will be ignored.
- Verify the loop: Read the current value at the control system or receiving end and check whether it matches the set value.
- Exit simulation: After the test is completed, exit simulation mode, and the instrument will resume normal measurement output.
Parameter Settings and Precautions
Key Parameters
| Parameter | Description | Typical Value |
|---|---|---|
| Simulation current range | Current output range that can be simulated | 4-20 mA |
| Simulation accuracy | Allowable deviation of output current | ±0.05 mA |
| Simulation duration | Automatic timeout time of simulation mode | Configurable (usually 10-30 minutes) |
| Alarm response | Alarm output status during simulation | Configurable (hold/ignore) |
Precautions
- Ensure that the safety interlock has been released or bypassed to avoid false actions triggered by the simulation signal.
- During simulation, the instrument will not respond to actual flow and must not be used for process control.
- Be sure to exit after simulation ends; otherwise, the instrument will continue to output a fixed current.
- If the simulated current does not match the receiving end display, check the loop resistance, cable polarity, and grounding.
Common Problems and Troubleshooting
- No current output: Check instrument power supply, fuse, and output terminal wiring.
- Large current deviation: Confirm whether the input impedance of the receiving end is within the allowable range (usually ≤500 Ω).
- Simulation value cannot be changed: It may be in write-protected state; a password must be entered or the lock must be released.
- Simulation mode exits automatically: Check the timeout setting or whether there is an alarm interruption.
Summary
Current simulation is an efficient tool for commissioning and maintenance of Endress+Hauser flow instruments. Through the steps and parameter descriptions in this article, engineering technicians can quickly complete loop verification, and procurement personnel can also use it to evaluate the functional completeness of the instrument. Correct use of this function can significantly improve on-site commissioning efficiency and system reliability.