Safety Testing of Medical Safety Testing of Medical Electrical Equipment Electrical Equipment

1 Hazards of Medical Electrical Equipment1 Hazards of Medical Electrical Equipment

1.1 Mechanical Hazards 1.1 Mechanical Hazards

1.2 Risk of fire or explos1.2 Risk of fire or explos

1.3 Absence of Functionion1.3 Absence of Functionion

1.4 Excessive or insufficient output1.4 Excessive or insufficient output

1.5 Infection1.5 Infection

1.6 Misuse1.6 Misuse

1.7 Risk of exposure to spurious electric 1.7 Risk of exposure to spurious electric currentscurrents

2 Physiological effects of electricity2 Physiological effects of electricity

2.1 Electrolysis2.1 Electrolysis

2.2 Burns2.2 Burns

2.3 Muscle cramps2.3 Muscle cramps

2.4 Respiratory arrest2.4 Respiratory arrest

2.5- cardiac arrest 2.5- cardiac arrest

2.6- ventricular fibrillation2.6- ventricular fibrillation

2.7- effect of frecqency on neuro-2.7- effect of frecqency on neuro-muscular stimulationmuscular stimulation

3 Classes and types of medical electrical equipment3 Classes and types of medical electrical equipment

4.1- class I equipment4.1- class I equipment

Figure 6. Symbols seen on earthed equipment

3.2 class IIequipment3.2 class IIequipment

Figure 7. Symbol for class II equipment.Figure 7. Symbol for class II equipment.

3.3 Class III equipment3.3 Class III equipment

SELV (Safety Extra Low Voltage )SELV (Safety Extra Low Voltage )

SELVSELV : :is defined in turn in the relevant is defined in turn in the relevant standard as a voltage not exceeding 25V standard as a voltage not exceeding 25V

ac or 60V dc. ac or 60V dc.

4.4 Equipment types4.4 Equipment types

Type Type Symbol Symbol Definition Definition

BB

Equipment providing a Equipment providing a particular degree of protection particular degree of protection against electric shock, against electric shock, particularly regarding particularly regarding allowable leakage currents and allowable leakage currents and reliability of the protective reliability of the protective earth connection (if present). earth connection (if present).

BFBF

As type B but with isolated As type B but with isolated or floating (F - type) or floating (F - type) applied part or parts. applied part or parts.

CFCF

Equipment providing a Equipment providing a higher degree of protection higher degree of protection against electric shock than against electric shock than type BF, particularly with type BF, particularly with regard to allowable leakage regard to allowable leakage currents, and having currents, and having floating applied parts. floating applied parts.

•3 Leakage currents3 Leakage currents

3.1 Causes of leakage currents3.1 Causes of leakage currents

a- the voltage on the conductor. a- the voltage on the conductor.

b- the capacitive reactance between the b- the capacitive reactance between the conductor and earth. conductor and earth.

c- the resistance between the conductor and earth c- the resistance between the conductor and earth

3.2 Earth leakage current3.2 Earth leakage currenttypes BF & CFtypes BF & CFALL CLASS I 500micr AALL CLASS I 500micr A

4.3 Enclosure leakage current4.3 Enclosure leakage currentfor class I,II,for class I,II, TYPES B&BF 100micrA, TYPES B&BF 100micrA, TYPE CF 10 micr A TYPE CF 10 micr A

4.4 Patient leakage current4.4 Patient leakage currenttype B &BF 100micrAtype B &BF 100micrAtype CF10micrA per part of apply parttype CF10micrA per part of apply part

Patient leakage current path from equipmentPatient leakage current path from equipment . Patient leakage current path to equipment.. Patient leakage current path to equipment.

4.5 Patient auxiliary current4.5 Patient auxiliary currentclassI&IIclassI&IIfor type B&BF&CF 10 micrAfor type B&BF&CF 10 micrA

6.10 Leakage current summary6.10 Leakage current summary

LeakagecLeakagecurrent urrent

Type B Type B Type BF Type BF Type CF Type CF

Earth Earth 0.50.5 1 1 0.50.5 11 0.50.5 11

Earth for Earth for fixed fixed

equipmenequipment t

5 5 10 10 5 5 1010 55 1010

Enclosure Enclosure 0.10.1 0.5 0.5 0.10.1 0.50.5 0.10.1 0.50.5

Patient Patient 0.10.1 0.5 0.5 0.10.1 0.50.5 0.010.01 0.050.05

Mains on Mains on applied applied

part part - - - - - - 55 -- 0.050.05

Patient Patient auxiliaryauxiliary

0.1 0.1 0.5 0.5 0.1 0.1 0.50.5 0.010.01 0.050.05

•5 Testing regimes and relevant documentation5 Testing regimes and relevant documentation

5.1 Type tests and routine tests5.1 Type tests and routine tests5.2 HTM 85.2 HTM 85.3 BS 5724 or IEC 606015.3 BS 5724 or IEC 606015.4 Hospital Equipment Information 955.4 Hospital Equipment Information 955.5 DB9801 Supplement 15.5 DB9801 Supplement 15.6 Medical Devices Directive5.6 Medical Devices Directive5.7 ESCHLE5.7 ESCHLE5.8 IEC 610105.8 IEC 610105.9 Hospital Equipment Information 1405.9 Hospital Equipment Information 140

5.10 When to test5.10 When to test

Medical electrical equipment should be inspected and Medical electrical equipment should be inspected and tested on the following occasions.tested on the following occasions.

a- On newly acquired equipment prior to being a- On newly acquired equipment prior to being accepted for use accepted for use

b- During routine planned preventative b- During routine planned preventative maintenance. maintenance.

c- After repairs have been carried out on c- After repairs have been carried out on equipmentequipment..

5.11 Recording test results5.11 Recording test results

5.12 Equipment Management Software 5.12 Equipment Management Software PackagesPackages

SAFETY ANALYSER SAFETY ANALYSER

6 Electrical Safety Tests6 Electrical Safety Tests

6.1 Normal condition and single fault conditions6.1 Normal condition and single fault conditions

**Normal operationNormal operation means provided for protection against means provided for protection against safety hazards are intactsafety hazards are intact

*Single fault*Single fault is a condition in which signal means of is a condition in which signal means of protectionprotection

•Against safety hazard is defective or external abnormal Against safety hazard is defective or external abnormal condition is present such as:condition is present such as:

•1- interruption of one protective earth conductor1- interruption of one protective earth conductor•2-the intrupt of on supply conductor of equipment2-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

6.2 Protective Earth Continuity6.2 Protective Earth Continuity

Applicable to Applicable to Class I, all types Class I, all types

Limit: Limit: 0.2 0.2

DB9801 DB9801 recommended?: recommended?:

Yes, at 1A or Yes, at 1A or less. less.

HEI 95 HEI 95 recommended?: recommended?:

Yes, at 1A or Yes, at 1A or less. less.

Notes: Notes: Ensure probe is Ensure probe is on a protectively on a protectively earthed point earthed point

6.3 Insulation Tests6.3 Insulation TestsApplicable to Applicable to Class I, all types Class I, all types

Limits: Limits: Not less than Not less than 50MΩ 50MΩ

DB9801 DB9801 recommended?: recommended?:

Yes Yes

HEI 95 HEI 95 recommended?: recommended?:

Yes Yes

Notes: Notes:

Equipment Equipment containing containing mineral insulated mineral insulated heaters may give heaters may give values down to values down to 1MΩ. Check 1MΩ. Check equipment is equipment is switched on. switched on.

Applicable to Applicable to Class II, all Class II, all types having types having applied parts applied parts

Limits: Limits: not less than not less than 50MΩ. 50MΩ.

DB9801 DB9801 recommended?: recommended?:

not less than not less than 50MΩ. 50MΩ.

HEI 95 HEI 95 recommended?: recommended?:

Yes Yes

Notes: Notes: Move probe to Move probe to find worst case find worst case

  6.4 Leakage current measuring device6.4 Leakage current measuring device

6.5 Earth Leakage Current6.5 Earth Leakage Current

Applicable to Applicable to

Class I Class I equipment, all equipment, all types types

Limits: Limits:

0.5mA in NC, 0.5mA in NC, 1mA in SFC or 1mA in SFC or 5mA and 10mA 5mA and 10mA respectively for respectively for permanently permanently installed installed equipment. equipment.

DB9801 DB9801 recommended?: recommended?:

Yes, in normal Yes, in normal condition only. condition only.

HEI 95 HEI 95 recommended?: recommended?:

Yes, in normal Yes, in normal condition only. condition only.

Notes: Notes:

Measure with Measure with mains normal mains normal and reversed. and reversed. Ensure Ensure equipment is equipment is switched on. switched on.

6.6 Enclosure leakage current6.6 Enclosure leakage current

Applicable

to

Class I and class II equipment, all types.

Limits: 0.1mA in NC, 0.5mA in SFC

DB9801

recommende

d?:

Yes, NC only

HEI 95 recommende

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.

6.7 Patient leakage current6.7 Patient leakage current

Applicable to Applicable to

All classes, type B All classes, type B & BF equipment & BF equipment having applied having applied parts. parts.

Limits: Limits: 0.1mA in NC, 0.1mA in NC, 0.5mA in SFC. 0.5mA in SFC.

DB9801 DB9801 recommended?: recommended?:

No No

HEI 95 HEI 95 recommended?: recommended?:

Yes, class I SFC Yes, class I SFC earth open circuit, earth open circuit, class II normal class II normal condition. condition.

Notes: Notes:

Equipment on but Equipment on but outputs inactive. outputs inactive. Normal and Normal and reverse mains. reverse mains.

Measurement of patient leakage current for each Measurement of patient leakage current for each

applied part in turnapplied part in turn

Applicable to Applicable to

Class I and class II, type CF (B & Class I and class II, type CF (B & BF for DB9801 only) equipment BF for DB9801 only) equipment having applied parts. having applied parts.

Limits: Limits: 0.01mA in NC, 0.05mA in SFC. 0.01mA in NC, 0.05mA in SFC.

DB9801 recommended?: DB9801 recommended?: Yes, all types, normal condition Yes, all types, normal condition only. only.

HEI 95 recommended?: HEI 95 recommended?: Yes, type CF only, class I SFC earth Yes, type CF only, class I SFC earth open circuit, class II normal open circuit, class II normal condition. condition.

Notes: Notes:

Equipment on but outputs inactive. Equipment on but outputs inactive. Normal and reverse mains. Limits Normal and reverse mains. Limits are per electrode. are per electrode.

6.8 Patient auxiliary current6.8 Patient auxiliary current

Applicable to Applicable to

All classes and types All classes and types of equipment having of equipment having applied parts. applied parts.

Limits: Limits:

Type B & BF - Type B & BF - 0.1mA in NC, 0.1mA in NC, 0.5mA in SFC.0.5mA in SFC.Type CF - 0.01mA Type CF - 0.01mA in NC, 0.05mA in in NC, 0.05mA in SFC. SFC.

DB9801 DB9801 recommended?: recommended?:

No. No.

HEI 95 HEI 95 recommended?: recommended?:

No. No.

Notes: Notes:

Ensure outputs are Ensure outputs are inactive. Normal inactive. Normal and reverse mains and reverse mains

6.9 Mains on applied parts6.9 Mains on applied partsApplicable to Applicable to Class I & class II, Class I & class II,

types BF & CF types BF & CF having applied having applied parts. parts.

Limit: Limit: Type BF - 5mA; Type BF - 5mA; type CF - 0.05mA type CF - 0.05mA per electrode. per electrode.

DB9801 DB9801 recommended?: recommended?:

No. No.

HEI 95 HEI 95 recommended?: recommended?:

No No

Notes: Notes: Ensure outputs are Ensure outputs are inactive. Normal inactive. Normal and reverse mains. and reverse mains. Caution required, Caution required, especially on especially on physiological physiological measurement measurement equipment. equipment.