Friday, February 6, 2009

1 Test device

The handheld test device is used to verify the proper operation of the trip unit, the energy transformers and current transformers as well as the tripping solenoid F5 and the data display

1.1 View

(1) LED for operating voltage indication

(2) Control buttons

(3) 6 LED's to show test results

1.2 Preparations

- Switch off and isolate the circuit-breaker

- Note the setting values of the overload release

- Switch off the earth-fault protection at the over current release, if available (Ig = OFF)

- Setting value IR = 1.0 In

- Interrupt external voltage supply for the electronic system, if available

- Remove the cap from the test connector X25 of the trip

1.3 Connection
: If this sequence is not followed then there may be false tripping& false result

(1) Test socket at the over current release

(2) SUB-D, 40-pole (test device) to socket connector, 40-pole or, with ETU release 2 and higher, SUB-D, 40-pole (test device) to plug connector, 40-pole

(3) Voltage supply

(4) Test device

1.4 Voltage supply

The test device is supplied by an AC power system 230 V or 115 V, 50/60 Hz. The factory setting is 230 V.The changeover switch is located on the printed circuit board inside the test device.

1.5 Operation

The status test starts immediately after connecting the voltage supply and queries the various components and parameters of the trip unit. If the status test is successful, the "ETU STATUS" LED will light up. Otherwise, the "ETU STATUS" LED will flash. It is possible to draw conclusions about the fault cause from the way in which it flashes

The status test can be repeated any time by pressing the "START" button for at least three seconds

Note: The status test is not supported by the over current releases type
ETU25B / ETU27B / ETU15B with identification number less than 253030xxxxxx / 273030xxxxxx / 150704xxxxxx .By pressing the "L" button for app. 3 seconds while switching on the test device power supply, the status test can be skipped for these types

Testing the current transformers

To test the current sensors and energy transformers, press the "START" button briefly (less than 2 sec).

A lit-up LED confirms the proper operation of the corresponding transformer. If an LED flashes, the corresponding transformer is not available, not properly connected or defective. Energy-transformers within CT’s will be tested "OK", if within the limits of 3.5 - 12 ohms and with an inductance above 300 mH.
External earth-fault-CT within the limits of 2.5 - 11 ohms and inductance above 500 mH will be tested similarly.
The length of the testing-period necessary may reach 65 sec.

Result of neutral CT check (for ETU release 2)

A flashing light (1 second on, 1 second off) indicates an error in the area of the transducer of the neutral conductor. The cause of this will either be a missing transducer (e.g. no external neutral CT connected), a missing connection to the transducer or a faulty transducer.
A rapid flashing light (0.5 seconds on, 0.5 seconds off) indicates an error in the area of the energy transformer of the neutral conductor.
The cause of this will either be a missing energy transformer (e.g. if an external neutral CT is connected), a missing connection to the energy transformer or a faulty energy transformer.

Testing the tripping function

Note Over current releases type ETU25B resp. ETU27B with an identification number smaller than 250205 xxxxxx resp. 270206xxxxxx do only react to a test of the L-tripping function.

- Charge the storage spring by hand

- Close

To test the tripping function, press one of the buttons "L", "S", "I", "N" or "G".

The test of tripping function will fail, if the corresponding protective a function of the ETU is not activated or available.

The circuit breaker trips after the time delay plus 2 seconds. The tripping reason can be inquired through the "QUERY" button at the trip unit. The trip cause storage function is available only, if the trip unit had been activated for least 10 min before tripping. Otherwise, the trip unit doesn't have the corresponding protective function or is defective.

Testing the display of the measured values

Once a tripping test has been carried out, if the ETU is not activated, the storage capability of the tripping reasons must be checked using the Query button. To check the correctness of the measured values in the display or via remote transmission press the "I" and "N" keys simultaneously.

A current is successively simulated via the measuring transformers in L1, L2, L3, N and G for 30 sec. The LED of the respective transformer will flash. The test can be considered successful if current is indicated in the corresponding position.

Activation of trip unit

To activate the trip unit press the “N“and “G“keys simultaneously

The trip unit is activated up to pressing another key.
With this function the “T.U.-Error“-LED can be checked, if the status test had finished with the error “Trip unit defective“.

1.6 Finishing

- Restore the noticed settings
- Mount the Cover on X25


  1. Hi itsmoneytime,
    Thanks for sharing such an useful information.You have properly illustrated how to verify the proper operation of the trip unit, the energy transformers and current transformers with a handheld testing device.Good work.Keep it up
    Circuit Breakers