Safety According to Iec 60364-7-710.2002-11

© Dipl.-Ing. W. BENDER GmbH&Co.KG 35305 Grünberg Germany www.bender-de.com Fxxx / 06.2002 1

Power in electrical safety

Electrical Safety for

• hospitals• private clinics• medical and dental practices• health care centres

according toIEC 60364-7-710:2002-11


Seminar topics

Why electrical safety in hospitals?

International standard for medical locations: IEC 60364-7-710

Classification of medical locations

Power supplies of main distribution

IT-system in group 2 rooms

Redundant power supply with change over system

Insulation fault location in IT-systems


Why is a maximum of electrical safety required ?

! The patient`s ability to reactnormally on possible hazards isreduced or eliminated.

! The electrical resistance of the skin may be reduced through the insertion of catheters and the likeinto natural or artificial orifices.

! The heart muscle is highlysensitive to electric currents(currents >10μA).

! Body functions are temporarily or continuously supported or substituted by medical electrical devices.

! Fire and explosion hazardsthrough anesthetics, disinfection orcleaning agents may occur.


Why is a maximum of electrical safety required?

! Electric and magnetic interferences, e.g. from the power system, may expose patients to hazards or may influence the function of medical electrical devices.

! Surgeries cannot be interrupted or repeated.

! Intensive care requires simultaneous application of several medical electrical devices.

! Permitted leakage currents may add to critical values.

! Long term recordings of patient data get lost in case of power failures.


The safety concept in healthcare facilities


A new standard since November 2002


General scope of IEC 60364-7-710

! IEC 60364-7-710 apply to electrical installations in medical locations so as to ensure safety of patients and medical staff.

!NOTE 1 It may be necessary to modify the existing electrical installationwhen a change of utilization of the location occurs. Special care should be taken where intracardiac procedures areperformed in existing installations.



Classificationof

medicallocations


Classification of medical locations710.30

!Classification of a medical location shall be made in agreement with ! the medical staff! health organization concerned or ! body responsible for the safety of workers in accordance with

national regulations.

! It is necessary that the medical staff indicate which medical procedureswill take place within the location. Based on the intended use, the appropriate classification for the location shall be determined.

! NOTE 1 Classification of a medical location should be related to the type of contactbetween applied parts and the patient, as well as the purpose for which the location is used.


Classification of medical locations (710.3.5-7)

Classification of groups 0 1 2Disconnection in case of the first fault

a) Patients at risk no no yes

b) Can the examination or treatment be yes yes norepeated or interrupted ?

Failure of the normal power supply

a) Patients at risk no no yes

b) Can the examination or treatment be yes yes norepeated or interrupted ?

Use of applied parts

a) Externally or invasively, but not for intracardiacapplication and where power failure can cause no yes yesdanger to life.

b) For intracardiac procedures in operating theatresand for vital treatment where discontinuity of the supply can cause danger to life. no no yes


Rooms of group 0 (710.3.5)

! Features ! Disconnection

• In the event of a first short circuit to exposed conductive parts or earth fault.

• Failure of the normal power supply! Examination and treatment

• Interruption/repitition can be toleratedExamination and treatment can beinterrupted and repeated.

! No use of applied parts

! ExamplesConsultation rooms, general wards

! Protective measures! According to IEC 60364-4-410

! Additional protection ! By equipotential bonding

! Safety power supply source! Safety lighting SV



! Features! Disconnection

• In the event of a single short circuit to exposed conductive parts or earth fault.

• Failure of the normal power supply! Examination and treatment

• Interruption/repitition can be tolerated! Applied parts

• used externally• Invasively to any part of the body (except

where 710.3.7 applies ->cardiac zone)

! Examples! Rooms for physiotherapy or hydrotherapy! Dialysis rooms


! Protective measures ! Double insulation! Safety extra-low voltage SELV! Functional extra-low voltage PELV, FELV! RCD in TN-S systems! IT system with insulation monitoring

! Supplementary protection! by equipotential bonding

! Safety power supply! Safety lighting

with safety power supply source



! Features! No disconnection

• In the event of a first short circuit toexposed conductive parts or earth fault

• Failure of the normal power supply ! Examination and treatment

• No interruption or repetition! Use of applied parts

• for intracardiac procedures • for vital treatment

! Examples! Operating theatres

(preparation, major surgery, post-operative treatment)! Intensive care rooms! Cardiac catheter rooms



! Protective measures ! Double insulation! Safety extra-low voltage SELV! Functional extra-low voltage PELV, FELV! RCD (not for feeding life-supporting

equipment)! IT system with insulation monitoring

for circuits feeding life-supporting equipment

! Supplementary protection ! by equipotential bonding

! Safety power supply! Safety lighting and safety power supply for

socket-outlets, devices, motors and the like.! Special safety power supply source for

luminaires of operating theatre tables and for life-supporting equipment, if required



List of examples for allocation of medical locations

Annex B Table B.1



Power suppliesin

medicallocations


Which power supply system is required by theIEC 60364-4-410 standard ?

1st letter: earthing of the current source

T = direct earthing one point of the current source

I = isolation of all active parts from earth

2nd letter: earthing conditions of the body of the electrical installation

T = the exposed conductive parts are earthed, independently of the earthing of any point of the current source which might exist

N =the exposed conductive parts are directly connected with the earthing point of the current source in AC systems, the earthed point is generally the neutral point


The use of earthed systems in hospitals

!Chapter 710.312.2:The TN-C system is not allowedin medical locations and medicalbuildings downstream of the main distribution board.


The TN-S system in medical locations (710.413.1.3)

! In final circuits of group 1 rated up to 32 A, RCDs ≤ 30 mA shall beused (additional protection).

!Care shall be taken to ensure that simultaneous use of many items of such equipment connected to the same circuit cannot cause unwanted tripping of the residual current protective device (RCD).

! In medical locations of group 1 and group 2, where RCDs are required, only type A or type B shall be selected, depending on the possiblefault-current arising.

!NOTE: It is recommended that TN-S systems are monitored to ensure the insulation level of all live conductors.



Fault current monitoring in theTN-S system of the main

distribution board


RCMS system - features

! The RCMS470 system monitors ! fault/residual currents! operating currents

! Modular system – up to 720 subcircuitsResponse value 1mA ... 2250A

! Use in medically used locations! Socket-outlet circuits which should not

fail! Alarm systems, safety devices! Air conditioning systems, EDP systems! Cold storage equipment with valuable

frozen goods! Canteen kitchens! Monitoring TN-S systems for stray

currents, loading of N-conductors



The electrical installation of group 2 rooms


TN-S system in medical locations of group 2 (710.413.1.3)

! In medical locations of group 2, protectionby automatic disconnection of supplyby means of RCD ≤ 30 mA shall only be used on the following circuits:

! circuits for the supply of operatingtables

! circuits for X-ray units! circuits for large equipment with a

rated power ≥ 5 kVA! circuits for non-critical electrical

equipment (non life support)


The medical IT-System (710.413.1.5)

! In group 2 medical locations, the medical IT system shall be used forcircuits supplying

!medical electrical equipment! systems intended for life support! surgical applications ! other electrical equipment located

in the "patient environment",! excluded equipment listed in

713.413.1.3.


Why isolated power ? – Increased operational safety

In IT systems! In the event of an insulation fault RF

only a very low capacitive current Ice flows

! Fuse does not trip! In the event of a single-pole earth fault,

the power supply is guaranteed! No interruption of operation! Alarm indicated by an A-ISOMETER®

In TN systems! A fault current flows determined by the earth

resistance and the insulation fault.

! IF<Ia Fuse does not trip -• Risk of malfunctions• No alarm

! IF >Ia Fuse trips -• Unexpected interruption of operation


Why isolated power ? – Low leakage currents

In TN systems! A high fault current can flow! The fault current is only limited by

the body impedance

In IT systems! The IT system is a small local

network with low leakage capacitances.

! The fault current is limited by the body impedance, the earthingresistance and the high impedanceof the fault loop.

! Hazards to persons and equipment arising from high fault currents are reduced.


Why isolated power ? – High degree of fire safety

In TN systems! When the fault current IF ≤ Ia

! Fuse does not trip! The electrical energy of the

fault current is transformed into thermal energy

! Fire risk at P ≥ 60 W = 260mA/230V).

In IT systems! A small current flows limited by

the high impedance of the fault loop.! Considerable less fire risk! Increased protection for persons

and equipment


Design of an IT system

! The IT system is supplied by an independent power source, e.g.

! Distribution / isolation transformer ! Control-power transformer! Generating set! Battery! Inverter of an UPS

! The IT system has no directconnection between live conductorsand earth.

! All exposed conductive parts of theelectrical installation are earthed.


Transformers for medical IT systems (710.512.1.1)

! Transformers shall be ! installed in close proximity to, inside or outside, the medical location ! placed in cabinets or enclosures to prevent unintentional contact with live

parts.

! Rated voltage Un on the secondary side of transformers ≤ 250 VAC

! Transformers according IEC 61558-2-15, with additional requirements:

! The leakage current of the output winding to earth and the leakagecurrent of the enclosure, when measured in no-load condition and the transformer supplied at rated voltage and rated frequency, ≤ 0.5 mA.

! Rated output of the transformers 0.5 kVA … 10 kVA.! For three-phase loads with an IT system a separate three-phase

transformer shall be provided for this purpose with output line-to-line voltage not exceeding 250 V.


Transformers for medical IT systems (710.512.1.1)

! short circuit voltage ≤ 3%

! no-load input current ≤ 3%

! inrush current ≤ 12 x rated input current

IEC 61558-2-15 Safety of power transformers, power supply units and similar-Part 2-15: Particular requirements for isolating transformers

for the supply of medical locations:


Transformers for medical IT systems

!Single phase transformers!ES0107 series! acc. to IEC 61558-2-15! 1…10 kVA!Vertical or horizontal

version, or installed in an enclosure

! Three-phase transformer!DS0107 series! acc. to IEC 61558-2-15! 1…10kVA!Vertical or horizontal

version, or installed in an enclosure


The insulation monitoring device (IMD) (710.413.1.5)

! For each group of rooms serving the same function, at least oneseparate medical IT system is necessary.

! The medical IT system shall be equipped with an insulationmonitoring device in accordance with IEC 61557-8 with the followingspecific requirements:

! a.c. internal impedance > 100 kOhm! the test voltage ≤ 25 V d.c.! injected current ≤ 1 mA peak, even under fault conditions! indication when insulation resistance ≤ 50kOhm! a test device shall be provided


Measuring principle of an IMD

! The insulation monitoring device isconnected between live conductors and earth.

! The measuring voltage Um generated by G is superimposed onto the system via the coupling Ri, the measuring resistance Rm and a low pass filter.

! An insulation fault RF betweensystem and earth closes themeasuring circuit.

! Im causes a voltage drop Umproportional to the insulation fault RF across the measuring resistance Rm.


A-ISOMETER 107TD47

****IT system ****R >500kΩ I = 20%

Indication-Interruptionsystem/earth connection

50...500 kOhm< 50 kOhmAlarm

< 50 uAmax. 1 mAMeasuring current

< DC12 V< DC 25 VMeasuring voltage

> 240 kOhm> 100 kOhmInternal impedance107TD47710.413.1.5Feature


! Overload and overcurrent protection is not allowed upstream and downstream in the feeder circuit of the medical IT system transformer (risk: unexpectedtripping)

! Fuses may be used for short circuit protection

! Monitoring of overload and high temperature for the medical IT transformer is required

! Socket outlet circuits in group 2 rooms:at each patient‘s place of treatment!Min. two separate circuits or! each socket- outlet shall be protected individually

against overcurrent

Protection of the IT system (710.413.1.5, 710.53.1, 710.55.3)


Load, temperature and insulation monitoring with 107TD47

Load

Insulation

Temperature


Remote alarm indications in rooms of group 2 (710.413.1.5)

! For each medical IT system, an acoustic and visual alarm systemshall be arranged at a suitable placeso that it can be permanently monitored by the medical staff:

! A green signal lamp to indicate normal operation! A yellow signal lamp which lights when the minimum value set for the

insulation resistance is reached. It shall not be possible for this light to be cancelled or disconnected

! An audible alarm which sounds when the minimum value set for the insulation resistance is reached. This audible alarm may be silenced.

! The yellow signal shall go out on removal of the fault and when thenormal condition is restored

! Note: Additionally overload and overtemperature of the IT system transformer must be indicated.


Remote alarm indicator MK2007CBM

!Clear digital seven-segment display for the indication of the insulation resistance (3 digits) and the load current (2 digits)

! Time and cost-saving installation via a two-wire connection (RS485).

!Easy-to-clean lexan front foil!Simple parallel indication through

two-wire interface!Power On LED => green!Alarm LEDs (insulation fault,

overtemperature, overload) => yellow


Remote alarm indicator MK2418

Alarm LED

illuminated two-line LC display

Power On LED

key, additional textscroll menu

key, TEST ISOMETERscroll menu

key, buzzer, acknowledgemenu ESC

! illuminated LC display

! Time and cost-saving installation via a two-wire connection(RS485)

! Easy-to-clean lexanfront foil

! Simple parallel indication throughtwo-wire interface

! Green Power On LED

! Yellow alarm LED


107TD47 107TD47

• Text display for information

• Two wire RS485 connection

• Alarms of several insulation monitors can be displayed

• Parallel indication possible

Remote alarm indicator for one or more IMD : MK2418


Remote alarm indicator MK2418C for additional information from inputs, e.g. medical gases

The data can be transferred to other MK2418C-12 installed in parallel.

MK 2418C-11

8 digital inputs, e.g.O2

CO2

Aircon

medicalgasRS485

107TD47


TM operator panels

• Large, backlit text display indicates user-programmable alarm text messages and additionalinformation.

• Three LEDs provide normal (green), warning (yellow), and alarm (yellow) indication.

• Different output/input options provide easy connection to other systems

• Installation of other technical equipment,e.g. operating theatre table control, paging systems, lighting, etc.


TM operator panels

! Alarm/warning messages are automatically stored with date and time stamp.

! 650 text messages can bestored in memory.

! Easy programming of textmessages via serial interface RS232 and PC software.

! Flush and surface mounted enclosures are available.



Notes for the electricalinstallation

of group 2 rooms


Supplementary equipotential bonding(710.413.1.6)

! In each medical location of group 1 and group 2, supplementaryequipotential bonding conductors shall be installed and connected to the equipotential bonding bus bar for the purpose of equalizingpotential differences between the following parts, located in the"patient environment":

! protective conductors! extraneous-conductive-parts! screening against electrical interference fields, if installed! connection to conductive floor grids, if installed!metal screen of the isolating transformer, if any


Equipotential bonding in group 2 rooms


Installations in group 2 rooms

!At each patient’s place of treatment, e.g. bedheads, the configurationof socket-outlets shall be as follows:

! either a minimum of two separate circuits feeding socket-outlets shall be installed or

! each socket-outlet shall be individually protected againstovercurrent.

!Where circuits are supplied from other systems (TN-S systems) in the same medical location, socket-outlets connected to the medical IT system shall either:

! be of such construction that prevents their use in other systems or! be clearly and permanently marked.



The safetypower supply

in medical locations


General power supply in hospitals(710.313.1 )

! In medical locations the distribution system should be designedand installed to facilitate the automatic change-over from the main distribution network to the electrical safety source feeding essential loads

! AV = Normal power supply source! SV = Safety power supply source! HV = Main distribution board


Safety services power supply sources (710.556.5.2)

!General requirements for safety power supply sources of group 1 and group 2

! In medical locations, a power supply for safety services isrequired which, in case of a failure of the normal power supplysource, shall be energized to feed the equipment stated in 710.556.5.2.2.1, 710.556.5.2.2.2 and 710.556.5.2.2.3 withelectrical energy for a defined period of time and within a pre-determined changeover period.

! If the voltage at the main distribution board drops in one orseveral line conductors by more than 10 % of the nominal voltage, a safety power supply source shall assume the supplyautomatically.


Equipment for changeover period > 15 s

! Equipment which is required for the maintenance of hospital services, may beconnected either automatically or manually to a safety power supply sourcecapable of maintaining it for a minimum period of 24 h. This equipment mayinclude, for example:

! sterilization equipment! technical building installations, in particular air conditioning,

heating and ventilation systems, building services and waste disposal systems

! cooling equipment! cooking equipment! storage battery chargers


Equipment for changeover period ≤ 15 s

! selected lifts for firemen! ventilating systems for smoke extraction;! paging systems!medical electrical equipment used in group 2 medical

locations which serves for surgical or other measures of vital importance. Such equipment will be defined by responsiblestaff

! electrical equipment of medical gas supply including compressedair, vacuum supply and narcosis (anaesthetics) exhaustion as well as their monitoring devices

! fire detection, fire alarms and fire extinguishing systems


Equipment for changeover period ≤ 15 s

!Escape routes! Lighting of exit signs! Locations for switchgear and controlgear for emergency

generation sets.!Distribution boards of the normal power supply and for power

supply for safety services.!Rooms in which essential services are intended. In each room at

least one luminaire shall be supplied from the power source forsafety services.

!Rooms of group 1 medical locations. In each room at least oneluminaire shall be supplied from the power supply source forsafety services.

!Rooms of group 2 medical locations. A minimum of 50 % of the lighting shall be supplied from the power source for safety services.


Changeover period for power supplies

!Changeover period less than or equal to 0.5 s (710.556.5.2.2.1)

! In the event of a voltage failure of one or more line conductors at the distribution board, a special safety power supplysource shall maintain

! luminaires of operating theatre tables and other essential luminaires, e.g. endoscopes, for a minimum period of 3 h.

! It shall restore the supply within a changeover period notexceeding 0.5 s.


!Power failures of the utility supply or damages of the supply cable should not have an impact on the continuity of the supply to the IT system:

!One supply cable with the risk of a complete loss of power supply

ZSV = Special safety power supply source

Power supply with one power line


! Two supply cables –main distribution: In case one cable fails, an automatic changeover unit initiates automatically a transfer to a second supply line

! changeover time <15s(time to start the generator)

ZSV = Special safety power supply source

Power supply with two supply lines


! Two supply lines with a safety power source! operating theatre! The second supply line is

supplied via an UPS system. This ensures the supply of life-supporting devices, independently from the utility supply and the emergencygenerator.

! Switchover time <0.5s with a battery capacity for 3 hours.

Power supply with two supply lines and a special safety power supply source


Installation example for an intensive care unitIT system for 4 beds

UFC107E65-12-B16


!Requirements of 710.413.1.5!For each group of rooms at least one separate IT system!Example 4 patient places

!Capacity balance!Capacity per bed 600 W 2400 W for 4 beds! In addition one high-capacity load 2000 W

- Total: 4400 W for 4 beds- IT system transformer 5 kVA

Application example "Intensive care unit"IT system for 4 patient places


Installation example for an operating theatre with a changeover period of t<15s (operating luminaire t<0.5s)


UMC107E - Switchover module andIT system monitoring

Voltage relay

Control device

Mains part supplying

remote alarm indicator

Wiring area

Connection terminals

Switching elements

Insulation, load and temperature monitoring


UMC107E - Switchover module andIT system monitoring

Voltage relay

Control device

Mains part supplying

remote alarm indicator

Wiring area


Switching elements

Insulation, load and temperature monitoring


Who knows where the insulation fault is ?


Who knows where the insulation fault is ?

! The problem! In intensive care locations several socket-outlets are arranged at every

patient place, sometimes up to 24 socket outlets and more! In an intensive care unit with 4 beds, for example, these are more than

90 socket outlets! In intensive care units usually no technical experts are present, but

medical personnel! If an insulation fault occurs, due to a defective device, for example,

nobody knows to which socket outlet the defective device is connected! In order to guarantee the patient's safety, the insulation fault must be

found as quick as possible.! But how ?

! The solution! Insulation fault location system EDS474


Design of an insulation fault location system


Basic function insulation fault location

!PGH... generates a test current, limited to harmless values, for a defined period of time.

! The test current isdetected and evaluatedby the insulation fault evaluator.

! This current flows via the insulation fault locationand is sensed by the CTs lying within the test current path.



Insulation fault location system

Switching elements

Voltage monitoring

Indicating device

Insulation, load current, and temperature monitoring device

Mains part for MK2418

Fuse

Insulation fault location system

Measuring current transformerInsulation fault locationsystem

Two-polecircuit breakerfor 24 subcircuits

UFC107E switchover module, IT system monitoringand insulation fault location system


Electrical safety in hospitals Résumé

! Classification of medical locations! IT-systems in group 2 rooms

! insulation, load, temperature monitoring! remote alarm indicators

! Redundant power supply with change over system! Insulation fault location in IT-systems

! Solutions for these requirements


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Documents

Safety According to Iec 60364-7-710.2002-11