Electric Safety Measurements And "First Measured Values - h/p/cosmos 150/50 mercury Operating And Service Manual

7.4.6.1

Electric safety measurements and "First Measured Values"

Immediately upon first installation at the customer's site an electric
safety test and measurement has to be performed for "Protective
Earth Resistance", "Isolation Resistance" and "Leakage Current".
The values are to be recorded in a special protocol [cos11690xx]
and marked as "first measured values".
Further details are described in chapter 8.3 entitled "Regular
inspections / examinations" / "Maintenance / safety inspections".
One copy of this protocol [cos11690xx] remains with the owner's
manual while the original of the protocol with the "first measured
values" should be sent to the manufacturer h/p/cosmos.
Picture: Example for electric safety testing device based on IEC 601-1
7.4.6.2 Potential equalization (only for medical treadmills)
The potential equalization cable must be connected to the connector on
the device plug and to the potential compensation bar within the medically
used room. During installation, connecting or disconnecting the potential
equalization, the running machine must not be connected to the power
supply. Protection against electric shock has to be provided in the finished
product/device.
Standard potential equalization cable (length 5m) with 4 mm
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7.4.6.3 General notes and benefits of potential equalization
The voltage of a conductor or body to earth is called the "potential" of this conductor or body. The earth is
electrically neutral and thus has the potential "zero". The unit of measurement for the potential is volt.
A conductor or body has the potential "zero" (earth potential) if it is conductively connected with the earth.
As a consequence of damage to the insulation, voltages may be transmitted to metal parts which do not belong to
the service circuit. This causes the development of potentials between the metal parts which might be dangerous
for man. If a man touches two different metal parts at a time - for instance an electrical device and a water pipe -
he bridges the existing potential and a current flows through his body. The flow of electric current through the body
of a human being could be mortal. A remedy for this is a potential equalization to zero potential. Potential
equalization therefore can be seen as an additional earthing (in addition to normal earthing included in power
cords) and improves the safety standard of medical devices and medical systems.
Potential equalization has the additional benefit of equal voltage potential on all involved metal housings of medical
devices of a medical system (for example treadmill, EMG, ECG and metabolic cart). Different voltage potentials on
housings could lead to false measurements during medical diagnosis, since the difference of voltage potential of
the medical devices within a system would interfere with voltage measurements (ECG, EMG, etc.) of the human
body.
Thus, potential equalization is also important for correct and valid measurements.
© 2012 h/p/cosmos sports & medical gmbh
When used in the medical field, all devices within the system have to be connected via a
potential compensation cable in "star-connection" with the potential compensation bar
within the designated room.
First connect the potential compensation (potential equalization) to the corresponding
plug pin (next to the main switch on the front) and then connect the mains plug.
During electric safety measurements and test (leakage currents, etc.), the potential
equalization cable isto be disconnected temporarily and re-connected after the electric
safety measurements and test.
file: n:\article\cos14310m5-v1_06hpc-en\20120504_cos14310m5-v1.06hpc-en_manual_h-p-cosmos_running_machine.docx
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safety, installation and commissioning
cross-section [cos10223]
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created 04.05.2012 printed 04.05.2012 page: 83 of 191