Check Box for Electric Safety Tests unit (CB-EST)

The box

The CB-EST has been designed to check the functionality of the electric safety tests unit which is included in, or which works together with, some of the Microplan test benches. It is not a calibration unit; its function is to verify periodically if the electric safety machine is still operating properly.

The box mainly includes a set of electric resistances, whose value is selected according to the limits of current, voltage and resistance that the Electric Safety Test (EST) switchboard produces and measures. This test box needs to be connected to the same sockets in the test bench to which the boiler under test is usually connected. A specific test sequence, supplied with the box, has to be launched on the control PC of the bench. The user shall periodically perform this test to get the functionality of the EST tests under control. A daily check for every bench is advisable, but the customer can decide a different frequency.

The test sequence

The sequence supplied with the box is a test sequence like others, with some particular features; once launched the test sequence drives the electric safety tests unit to perform the tests and guides the operator in all the phases. The ground continuity, insulation and dielectric strength tests are performed, each one twice, as follows:

  • the first time the limits are set in the EST switchboard so that, considering the value of the resistances in the box, the test should end with a OK result. If this happens it means that the EST switchboard is correctly working therefore the sequence will continue with the following tests. If this is not the case, the test sequence will stop showing an error message.
  • the second time the limits in the EST switchboard are set in such a way that, considering the value of the resistances in the box, the test should end with a NOK result. If this happen it means that the switchboard is working well therefore the sequence will continue with the following tests. If this is not the case, the test sequence will stop showing an error message.