Electrical safety testing
Welch Allyn recommends performing ground continuity and leakage current tests after
all open-case repairs and dielectric strength testing is not recommended.
Note Perform dielectric strength testing only if there is a reason to doubt the
integrity of the electrical insulation (e.g. multiple trips of a residual-current
device or liquid ingress of a saline solution). If you determine this test
should be performed, return the device to Welch Allyn for service.
These recommendations trace to EN/IEC 60601-1 – Medical Electrical Equipment – Part
1: General Requirements for Basic Safety and Essential Performance or EN/IEC 62353 –
Medical Electrical Equipment – Recurrent Test and Test After Repair of Medical Electrical
Equipment.
Because of the variability of test equipment in the field, Welch Allyn does not include
specific instructions to perform electrical safety tests. When performing electrical safety
tests, refer to your test equipment manuals for detailed instructions to ensure proper
test equipment setup that aligns with the appropriate standard. The following table
provides connections and test limits to assist you in performing these tests.
Test Limits
Ground continuity (see Note above) Ground continuity from EP stud (equipotential terminal)* to the Gnd pin of the
IEC power connector shall be no greater than 0.1 ohms.
Leakage current (see Note above) Leakage current shall be less than 500 µA from EP stud* to mains (Line and
Neutral pins of the IEC power connector).
Insulation resistance Dielectric strength shall be 500 V (DC) EP stud* to IEC mains (Line and Neutral
pins of the IEC power connector), and insulation resistance is measured.
* To locate the equipotential terminal, see “Controls, indicators, and connectors."
Devices with an External Power Supply
The power bricks are CB Certified and UL Listed; they meet ALL of the requirements
that the Medical Device standard requires for power supplies. The manufacturer is
required to perform 100% electrical safety testing on all of their power bricks prior to
shipment. Welch Allyn does not perform nor recommend testing on these external
power bricks because additional testing would put undue stress on the insulation system
and possibly cause premature failures in the field. Open case repairs of devices with
external power supplies are only dealing with DC circuitry and robust isolation circuits
built into the printed circuit boards. No additional after-servicing testing is required in that
instance. The patient isolation systems within the device (Temperature Probe, SpO2
sensor, CO2 sensor, ECG sensor, etc.) all have visible isolation gaps built into the printed
circuit board. The quality control on the PCB and the thorough type-testing performed by
the testing agency (ETL) eliminates the need for further testing on the devices that are
downstream from the mains isolation device.
Devices with an Internal Power Supply
The internal power supplies are CB Certified and UL Registered. These power supplies
are an open frame style (no protective enclosure). Therefore, the products that contain
an internal power supply require electrical safety testing. Open case repairs of devices
with an internal power supply require the recommended testing because those devices
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Functional verification and calibration overview Connex
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