How to Test a Level Switch?
To test a level switch, you need to verify that it functions correctly by simulating the conditions it is designed to respond to. This can be done by applying pressure to the diaphragm or filling a container to a certain level. The goal is to confirm that the switch activates and sends signals according to its specifications.
Preparations Before Testing
Before testing a level switch, ensure the following steps are completed:
Read the Manufacturer’s Manual
Each level switch has unique specifications. For models like the NV 14P, it is essential to understand features such as the diaphragm’s movement range and the electrical connections of the micro switch.
Ensure Safe Operation
Disconnect power and make sure the workspace is safe.
If the level switch is installed in a silo or container, empty it of material to prevent unexpected reactions.
Inspect ComponentsCheck the diaphragm, connections, and any cables for damage. For models like NV 14P-KM, it is particularly important to ensure that the compensation diaphragm is intact.
Testing Methods for a Level Switch
Here are some key steps to follow when testing a level switch:
1. Functional Test with Manual Pressure
Purpose: Verify that the diaphragm and micro switch work as expected.
How to test:
Gently press the diaphragm with your hand or a tool.
If the switch is properly connected to an electrical circuit, it should activate when the diaphragm moves sufficiently (around 3-4 mm for models like NV 14P).
Expected result:
A clicking sound from the micro switch or activation of an indicator light/signal device confirms that the level switch is functioning correctly.
2. Testing in the Application Environment
Purpose: Ensure the level switch works in its actual environment.
How to test:
Fill the container with material up to the switch’s level.
If the level switch is installed for overfill protection, make sure the material reaches the diaphragm and activates the switch.
For systems with a compensation diaphragm, check that pressure adjustments occur without errors.
Expected result:
The system should stop filling or send a signal to the operator when the correct level is reached.
3. Electrical Connection Test
Purpose: Verify that the level switch transmits the electrical signal correctly.
How to test:
Use a multimeter to measure voltage or resistance across the switch terminals.
When the diaphragm activates the micro switch, the multimeter should display a change, such as a closed circuit.
Expected result:
A proper electrical signal (e.g., 15 A at 125 VAC for NV 14P) indicates correct operation.
Common Issues and Solutions
During testing, the following issues may occur:
The diaphragm does not activate
Check if material is stuck or if the diaphragm is damaged. Clean or replace it if necessary.
No electrical signal
Verify cable connections and the status of the micro switch. Use a multimeter to troubleshoot the circuit.
Incorrect installation
If the level switch does not respond properly, improper installation might be the cause. For models like NV 14P-KM, check that the compensation diaphragm is correctly installed and that air pressure is balanced.
Importance of Testing
Regularly testing the level switch is crucial to ensuring reliable operation and preventing production disruptions. A properly functioning level switch helps prevent overfilling, protects equipment, and optimizes process flows.
Summary
Testing a level switch involves simulating the conditions it is designed to monitor. By manually pressing the diaphragm, performing electrical tests, and testing it in its actual application, you can ensure it works correctly. Regular testing, especially for models like NV 14P from Level Switch Sweden, is a simple but essential measure to maintain safe and efficient operation in industrial processes.