Table of Contents

• Basic test procedures
  • Test 1: Test for the MBR relay without the sensor connected
  • Test 2: Test for the MBR relay with the sensor connected
  • Summary of tests
• Additional field voltage tests for the MBR relay
• Tests with the MBR sensor disconnected from the relay
  • Test 1: Continuity test between the blue and black wires
  • Test 2a: Sensor integrity test - part 1
  • Test 2b: Sensor integrity test - part 2

Introduction

This article presents the procedures required to perform functionality tests on the MBR equipment and its sensor.

Basic test procedures

Test 1: Test for the MBR relay without the sensor connected

With jumpers installed in the correct positions, the table below shows the connections that must be made on the MBR relay and the expected results.

Test 2: Test for the MBR relay with the sensor connected

1. Connect the sensor directly to the MBR relay (the sensor does not need to be connected to the CP-MBR for this test);

2. Turn on the power supply to the MBR relay;

3. Take a container with clean water or oil (a glass is sufficient);

4. With the sensor in the air, check the alarm status indicated on the MBR (the red LED must be off) and the alarm contact must be indicated as shown in the table below;

5. Place the sensor into the container with clean water or oil; this should activate the alarm;

6. The alarm contact must behave according to the jumpers in the table below.

Summary of tests

1. If the MBR relay passes test 1, the relay is operating normally;

2. If the MBR relay connected to the sensor passes test 2, both the relay and the sensor are operating normally;

3. If the relay passes test 1 but fails test 2, the sensor is defective.

Additional field voltage tests for the MBR relay

1 - MBR with all sensor cables connected:

2 - MBR relay with poor contact on the black wire of the MBR sensor  (connected to terminal 14):

3 - MBR relay with poor contact on the white wire of the MBR sensor (connected to terminal 6): 

4 - MBR relay with poor contact on the blue wire of the MBR sensor (connected to terminal 7): 

5 - MBR relay with poor contact on the red wire of the MBR sensor (connected to terminal 8): 

6 - MBR relay with all sensor cables disconnected: 

Tests with the MBR sensor disconnected from the relay

Test 1: Continuity test between the blue and black wires

Disconnect all sensor cables from the MBR relay and, using a multimeter set to the continuity test function, connect the test leads to the blue and black cables of the sensor. The multimeter must confirm that there is indeed continuity; otherwise, the sensor must be replaced.

Test 2a: Sensor integrity test - part 1

1. Keep the red and blue cables connected to the MBR relay (check whether there is a voltage of approximately 12 Vdc between them);

2. Measure the sensor output voltage with the multimeter, between the white (+) and black (-) cables;

3. With the sensor deactivated, i.e., without contact with liquid media, the output voltage must be 12 Vdc;

4. With the sensor in alarm state, i.e., in contact with liquid or if the sensor is damaged, the output voltage will be around 0 Vdc.

If the voltage is close to 0 V at the output, perform the following test:

Test 2b: Sensor integrity test - part 2

1. Disconnect all sensor cables from the MBR;

2. Using a multimeter in diode test mode, measure between the white (+) and black (-) cables, as shown in the figure below;

Figure 1 - Measurement of the MBR sensor cables

3. If the reading is approximately 0 V, the sensor is damaged and must be replaced;

4. If the voltage is greater than zero or if the multimeter displays overload (OL), the alarm is likely genuine and transformer disconnection should be scheduled for inspection and maintenance.

If there are any issues or if you experience any difficulties with any of the tests presented in this guide, please do not hesitate to contact us!

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