CLASSES AND TYPES OF MEDICAL ELECTRICAL, NURATIQAH BINTI SHAMSUDDIN …
CLASSES AND TYPES OF MEDICAL ELECTRICAL
The type of protection against electrical shock is either double insulation or reinforced insulation.
In dual insulated appliances, the first layer of insulation provides essential protection. If the basic protection fails, additional protection is provided by a second insulation layer which prevents contact with live parts.
Class II medical electrical devices should be fused in either the mains conductor or in both conductors at the equipment end of the supply lead if the equipment has a working ground.
Symbol in class II
Has a protective earth.
The fundamental means of protection is the insulation between living parts and exposed conductive parts, such as the metal enclosure.
Live and neutral conductors should have fuses at the end of the mains supply, so that extra protection is operational when the equipment is attached to an improperly wired socket outlet.
Symbol in class I
Some equipment specifications, such as that in which electric shock safety is based on the fact that there are no voltages higher than extra low voltage (SELV) security.
In the related norm, SELV is in turn, specified as a voltage not exceeding 25V ac or 60V dc.
In reality, such equipment is either powered by a battery or supplied by a transformer SELV.
It is important to note that the existing IEC quality requirements for medical electrical devices do not accept Class III equipment because the voltage restriction is not considered necessary to guarantee patient safety.
When attached to the mains, battery-powered equipment may be operated, but it must be inspected for protection as either class I or class II equipment.
Equipment that provides a specific degree of protection against electric shock, in particular with regard to acceptable leakage currents and the durability (if present) of the protective earth link.
As type B but with a component or parts isolated or floating (F - type) added.
Equipment which provides a higher degree of electrical shock safety than Type BF, in particular with regard to permissible leakage currents and floating components.
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