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Safety Testing of Medical Electrical Equipment. 1 Hazards of Medical Electrical Equipment 1.1 Mechanical Hazards 1.2 Risk of fire or explos 1.3 Absence.

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Presentation on theme: "Safety Testing of Medical Electrical Equipment. 1 Hazards of Medical Electrical Equipment 1.1 Mechanical Hazards 1.2 Risk of fire or explos 1.3 Absence."— Presentation transcript:

1 Safety Testing of Medical Electrical Equipment

2 1 Hazards of Medical Electrical Equipment 1.1 Mechanical Hazards 1.2 Risk of fire or explos 1.3 Absence of Functionion 1.4 Excessive or insufficient output 1.5 Infection 1.6 Misuse 1.7 Risk of exposure to spurious electric currents

3 2 Physiological effects of electricity 2.1 Electrolysis 2.2 Burns 2.3 Muscle cramps 2.4 Respiratory arrest 2.5- cardiac arrest 2.6- ventricular fibrillation

4 2.7- effect of frecqency on neuro- muscular stimulation

5 3 Classes and types of medical electrical equipment 4.1- class I equipment 4.1- class I equipment Figure 6. Symbols seen on earthed equipment

6 3.2 class IIequipment Figure 7. Symbol for class II equipment. Figure 7. Symbol for class II equipment.

7 3.3 Class III equipment SELV (Safety Extra Low Voltage ) SELV :is defined in turn in the relevant standard as a voltage not exceeding 25V ac or 60V dc.

8 4.4 Equipment types TypeSymbolDefinition B Equipment providing a particular degree of protection against electric shock, particularly regarding allowable leakage currents and reliability of the protective earth connection (if present). BF As type B but with isolated or floating (F - type) applied part or parts. CF Equipment providing a higher degree of protection against electric shock than type BF, particularly with regard to allowable leakage currents, and having floating applied parts.

9 3 Leakage currents3 Leakage currents 3.1 Causes of leakage currents a- the voltage on the conductor. b- the capacitive reactance between the conductor and earth. c- the resistance between the conductor and earth

10 3.2 Earth leakage current types BF & CF ALL CLASS I 500micr A

11 4.3 Enclosure leakage current for class I,II, TYPES B&BF 100micrA, TYPE CF 10 micr A

12 4.4 Patient leakage current type B &BF 100micrA type CF10micrA per part of apply part Patient leakage current path from equipment. Patient leakage current path to equipment.

13 4.5 Patient auxiliary current classI&II for type B&BF&CF 10 micrA

14 6.10 Leakage current summary Leakagec urrent Type B Type BF Type CF Earth Earth for fixed equipmen t Enclosure Patient Mains on applied part Patient auxiliary

15 5 Testing regimes and relevant documentation5 Testing regimes and relevant documentation 5.1 Type tests and routine tests 5.2 HTM BS 5724 or IEC Hospital Equipment Information DB9801 Supplement Medical Devices Directive 5.7 ESCHLE 5.8 IEC Hospital Equipment Information 140

16 5.10 When to test Medical electrical equipment should be inspected and tested on the following occasions. a- On newly acquired equipment prior to being accepted for use b- During routine planned preventative maintenance. c- After repairs have been carried out on equipment.

17 5.11 Recording test results 5.12 Equipment Management Software Packages

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19 SAFETY ANALYSER

20 6 Electrical Safety Tests 6.1 Normal condition and single fault conditions * Normal operation means provided for protection against safety hazards are intact *Single fault is a condition in which signal means of protection Against safety hazard is defective or external abnormal condition is present such as: Against safety hazard is defective or external abnormal condition is present such as: 1- interruption of one protective earth conductor 1- interruption of one protective earth conductor 2-the intrupt of on supply conductor of equipment 2-the intrupt of on supply conductor of equipment 3 -the short circuiting of either constituent part of 3 -the short circuiting of either constituent part of double insulation double insulation

21 6.2 Protective Earth Continuity Applicable to Class I, all types Limit:0.2 DB9801 recommended?: Yes, at 1A or less. HEI 95 recommended?: Yes, at 1A or less. Notes: Ensure probe is on a protectively earthed point

22 6.3 Insulation Tests Applicable to Class I, all types Limits: Not less than 50MΩ DB9801 recommended?: Yes HEI 95 recommended?: Yes Notes: Equipment containing mineral insulated heaters may give values down to 1MΩ. Check equipment is switched on.

23 Applicable to Class II, all types having applied parts Limits: not less than 50MΩ. DB9801 recommended?: not less than 50MΩ. HEI 95 recommended?: Yes Notes: Move probe to find worst case

24 6.4 Leakage current measuring device 6.4 Leakage current measuring device

25 6.5 Earth Leakage Current Applicable to Class I equipment, all types Limits: 0.5mA in NC, 1mA in SFC or 5mA and 10mA respectively for permanently installed equipment. DB9801 recommended?: Yes, in normal condition only. HEI 95 recommended?: Yes, in normal condition only. Notes: Measure with mains normal and reversed. Ensure equipment is switched on.

26 6.6 Enclosure leakage current Applic able to Class I and class II equipment, all types. Limits:0.1mA in NC, 0.5mA in SFC DB980 1 recom mende d?: Yes, NC only HEI 95 recom mende d?: Yes, class I SFC earth open circuit, class II NC. Notes: Ensure equipment switched on. Normal and reverse mains. Move probe to find worst case. Figure 13. Measurement of Enclosure Leakage Current.

27 6.7 Patient leakage current Applicable to All classes, type B & BF equipment having applied parts. Limits: 0.1mA in NC, 0.5mA in SFC. DB9801 recommended?: No HEI 95 recommended?: Yes, class I SFC earth open circuit, class II normal condition. Notes: Equipment on but outputs inactive. Normal and reverse mains.

28 Measurement of patient leakage current for each applied part in turn Applicable to Class I and class II, type CF (B & BF for DB9801 only) equipment having applied parts. Limits: 0.01mA in NC, 0.05mA in SFC. DB9801 recommended?: Yes, all types, normal condition only. HEI 95 recommended?: Yes, type CF only, class I SFC earth open circuit, class II normal condition. Notes: Equipment on but outputs inactive. Normal and reverse mains. Limits are per electrode.

29 6.8 Patient auxiliary current Applicable to All classes and types of equipment having applied parts. Limits: Type B & BF - 0.1mA in NC, 0.5mA in SFC. Type CF mA in NC, 0.05mA in SFC. DB9801 recommended?: No. HEI 95 recommended?: No. Notes: Ensure outputs are inactive. Normal and reverse mains

30 6.9 Mains on applied parts Applicable to Class I & class II, types BF & CF having applied parts. Limit: Type BF - 5mA; type CF mA per electrode. DB9801 recommended?: No. HEI 95 recommended?: No Notes: Ensure outputs are inactive. Normal and reverse mains. Caution required, especially on physiological measurement equipment.

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