Electro-medical devices must be tested according to DIN EN60601 (VDE 0750 ). Compared to other safety tests, these devices should be tested to EN60601 standard – particularly with regards to leakage current measurement. The measurement of leakage currents takes place at ambient temperatures without prior moisture treatment. Since the specimens are often connected directly to the patient, the VDE Testing requires a very detailed examination. Each part of the examination is to ensure that compliance with the above provisions is ensured. There are several conscientious checks which ensure consistent manufacturing of the products. In the leakage test, according to EN60601, distinction is made between: Earth leakage current, patient leakage current and patient auxiliary current.
These tests are carried out after assembly on the complete unit and consist of:
a) Functional test
b ) Protective conductor test to 25 AAC
c ) Measurement of the leakage current up to max. 10 mA.
d ) Dielectric strength.
The high voltage test for checking the dielectric strength is given by the table on page 3 of the EN60601 standard. Depending on the degree of insulation, the voltages which can be tested vary between 230 V and 4000 V. A routine test you can perform, in accordance with EN60601 is to use the compliant electrical safety tester ST400.
Leakage current test according to EN 60601
The leakage current is an unwanted current, determined by the metric ‘leakage current.’ The leakage current is determined by which current flows through a “patient” to ground. In case of a failure of the PE connection, there are three different test methods A1, A2 and B.
a1 = L against PE
a2 = N against PE
b = L/N against PE