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Ensuring the Safety of Medical Devices

The purpose of safety testing medical electronic equipment is to be sure that a device is safe from electrical hazards to the patient and caregivers. There are a number of global standards that serve as the ruling body on how medical products will be tested. One in particular, IEC60601-1, has been accepted and implemented around the world. IEC60601-1 is mainly intended for product development where safety considerations must be taken into account early in the design phase of a product, however much of it applies to production line testing to ensure manufacturer are shipping safe products.

Vital areas of medical device electrical safety testing include hipot test or dielectric breakdown, leakage current, insulation resistance and ground bond testing. To better understand the differences in these tests and others, the papers below examine the purpose and techniques for each test then offers a detailed discussion on ensuring the safety of medical electronics.

Ensuring the Safety of Medical Devices
Electrical Safety Testing 101
A Practical Guide to Dielectric Testing
IEC60601-1 And Your Electrical Medical Products
Testing to IEC60601 Standards

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medical device test systems - Chroma

Automated Test Solutions

Chroma’s Sentinel Systems are fully customizable automated test solutions designed specifically for medical device electronics, including R&D and production testing, in order to meet global compliance requirements. Sentinel Systems can provide complete Electrical Safety Testing to IEC60601-1 and IEC 60601-2-49 (Multifunctional Patient Monitoring Equipment).

Sentinel I Medical Test System
19032 Hipot Analyzer + CaptivATE Automation Software

Automated Medical Device Safety Testing to IEC/EN/UL/CSA 60601-1. Test Hipot, Ground Bond, Insulation Resistance, Patient Leakage, Earth Line Leakage, Enclosure Leakage and Patient Auxiliary Leakage. CaptivATE Software provides data logging of electrical tests with an easy to use programmable interface. The Sentinel I System accommodates Class I, Class II and internally powered medical devices with the following specifications:

  • Mains Power up to 4400VA, 0-300Vac
  • 1 B-Type Patient Connection

Medical device test - Sentinel II - ATE

Sentinel II Medical Test System
19032 Hipot Analyzer + CaptivATE + Programmable AC Power

Automated Medical Device Safety Testing to IEC/EN/UL/CSA 60601-1. Sentinel II saves time by scanning patient connections for leakage current without powering down the medical device. The Sentinel II System can be configured to accommodate Class I, Class II, mains and internally powered medical devices with the following configurations:

  • Mains Power supply up to 4000VA, 0~300VAC @ 15~1kHZ
  • Up to 1 B-Type Patient Connection

medical device test - sentinel III - ATE

Sentinel III Medical Test System
19032 Hipot Analyzer + CaptivATE + 1500VA or 800VA AC Source + Matrix 8000 Scanning System

Automated Medical Device Safety Testing to IEC/EN/UL/CSA 60601-1 and IEC60601-2-49 (Multifunctional Patient Monitoring Equipment). Sentinel III also scans patient connections for leakage current without powering down the medical device. The Sentinel III System can accommodate Class I, Class II, mains and internally powered medical devices with the following configurations:

  • Mains power input up to 4000VA, 0~300Vac @ 15~1kHz
  • Up to 16 B, BF, or CF patient connections
  • 4 signal inputs/signal outputs
  • Other custom configurations available

CaptivATE Automation Software 

CaptivATE provides an off-the-shelf test platform for automating hipot, leakage current, and functional tests. By automating the loading of test setups, sharing test setups plantwide, and combining safety and functional tests into one system, CaptivATE increases efficiency and productivity. For medical devices, software supports IEC60601-1 test requirements, digitally stores product test certificates, and provides IQOQ protocol documentation. Also, supports legacy QuadTech instruments.

medical device test - captivate automation software

hipot test - chroma

Hipot Test Equipment

Hipot testing or dielectric strength testing determines the suitability of the dielectric or insulation barrier between hazardous and non-hazardous parts. The IEC60601-1 standard and its supporting standards specify the voltage to be applied to the device under test (DUT) and the acceptance criteria, usually: ‘no breakdown or repeated flashover shall occur’. For example: The supporting standard UL2601-1 in the product category of medical equipment, specifies the dielectric withstand test as: the test voltage = 1250V AC for 120V mains (1500V AC for 220V mains) or 2121V DC; the maximum current = ‘no arc-over or breakdown’; and the test time = 60 seconds.

hipot tester - 19070 - chroma

19070 Sentry Hipot Tester
Hipot 5kVac | 6kVdc
AC only or AC | DC | IR

A compact, low cost hipot tester. Provides AC hipot testing only or AC and DC hipot, 1kV insulation resistance.

19050 Guardian Hipot Tester
Hipot 5kVac | 6kVdc
AC | DC | IR

The Guardian 19052 is capable of AC/DC/IR Hipot testing and insulation resistance (IR) measurements. The Guardian 19053 combines both AC and DC Hipot tests and IR measurements with 8HV scan channel capabilities.

Hipot tester analyzer

19032 Guardian Electrical Safety Analyzer
Hipot 5kVac | 6kVdc
AC/DC/IR/GB/LC/Dynamic Function

The 19032 series combines Hipot, Insulation Resistance (IR), Ground Bond (GB), Leakage Current (LC)/AC LC/DC LC and Dynamic Function Tests. Space savings can be up to 50% of production line space, by eliminating multiple safety test instruments. The 19032 increases  efficiency of electrical safety testing during manufacturing and reduces associated labor costs.

Multi channel hipot tester

19020 Guardian Multi-Channel Hipot Tester
Hipot 5kVac | 6kVdc
AC/DC/IR

Hipot leakage current of all channels at the same time and conduct tests on up to 100 UUTs simultaneously.

medical_leakage_current

Leakage Current Test

Leakage current is the residual flow of current after HIGH voltage (greater than normal operating voltage) has been applied to the device under test (DUT). This is the current measured in a hipot test. Line leakage current is that measured at 110% of highest rated operating voltage and highest rated frequency. The device under test is turned on and the line leakage is measured across a circuit that simulates the impedance of the human body. There are four types of leakage current: Earth, Touch/Chassis (Enclosure), Patient (Applied Part) and Patient Auxiliary.

Four types of leakage current:

  • Earth leakage is that line leakage current measured when the ground connector is open, a circuit that simulates the impedance of the human body is inserted and the voltage is measured across it.

  • Touch/Chassis (Enclosure) leakage is that line leakage current measured by connecting the circuit that simulates the impedance of the human body to any exposed part of the chassis of the DUT. This simulates someone touching the enclosure/chassis of the DUT.

  • Patient (Applied Part) leakage is that line leakage measured from or between applied parts of the DUT such as the current that might flow from patient leads and sensors on a medical device.

  • Patient Auxiliary leakage is that line leakage current flowing in the patient in NORMAL use between applied parts of the DUT and not intended to produce a physiological effect.

Hipot tester analyzer

19032 Guardian Electrical Safety Analyzer
Hipot 5kVac | 6kVdc
AC/DC/IR/GB/LC/Dynamic Function

The 19032 series combines Hipot, Insulation Resistance (IR), Ground Bond (GB), Leakage Current (LC)/AC LC/DC LC and Dynamic Function Tests. Space savings can be up to 50% of production line space, by eliminating multiple safety test instruments. The 19032 increases  efficiency of electrical safety testing during manufacturing and reduces associated labor costs.



medical_insulation_resistance

Insulation Resistance Test

An Insulation Resistance (IR) test measures the total resistance between any two points separated by electrical insulation. The purpose is to determine the strength of the dielectric material (insulation) by stressing it with a high voltage. Voltage (typically 50-1000V DC) is applied to the device under test (DUT) and current is measured. That current flow is made up of three components: dielectric absorption, charging current and leakage current. Dielectric absorption is the physical occurrence of a device absorbing (retaining) charge like an electrolytic capacitor. Charging current represents itself in the insulation of a device as an instantaneous rise with the applied voltage, and then quickly decays to zero. Leakage current is the component flowing through the insulation after the initial charge of the device. Leakage current is equal to the applied voltage divided by the insulation resistance of the device under test. Remember this residual leakage current from a HIGH voltage test is different than that measured under NORMAL operating conditions.

hipot tester - 19070 - chroma

19070 Sentry Hipot Tester
Hipot 5kVac | 6kVdc
AC only or AC | DC | IR

A compact, low cost hipot tester. Provides AC hipot testing only or AC and DC hipot, 1kV insulation resistance.

19050 Guardian Hipot Tester
Hipot 5kVac | 6kVdc
AC | DC | IR

The Guardian 19052 is capable of AC/DC/IR Hipot testing and insulation resistance (IR) measurements. The Guardian 19053 combines both AC and DC Hipot tests and IR measurements with 8HV scan channel capabilities.

Hipot tester analyzer

19032 Guardian Electrical Safety Analyzer
Hipot 5kVac | 6kVdc
AC/DC/IR/GB/LC/Dynamic Function

The 19032 series combines Hipot, Insulation Resistance (IR), Ground Bond (GB), Leakage Current (LC)/AC LC/DC LC and Dynamic Function Tests. Space savings can be up to 50% of production line space, by eliminating multiple safety test instruments. The 19032 increases  efficiency of electrical safety testing during manufacturing and reduces associated labor costs.

medical_ground_bond

Ground Bond Testing

A Ground Continuity (GC) test checks that there is a connection between exposed conductive parts and the ground of the power cord being tested. A low current signal,typically less than 1 Amp is applied to the device under test. A Ground Bond test determines the strength of that ground connection with a high current signal, typically 25Amps. IEC60601-1 specifies that user-accessible conductive parts connected to the safety ground be tested with a current of either 25A or 1.5 times the product’s current consumption, whichever is greater. The current must source from a maximum no-load voltage of 6V AC. The test is performed for 5 to 10 seconds. The resistance of this ground path equals test current divided by voltage drop. Ohms Law: V=RI, solving for R, R = V/I = 6V/25A = 0.24Ω. IEC60601-1 specifies that the resistance be <0.1Ω on equipment with a detachable power cord and <0.2Ω for equipment with a permanently attached power cord.

Ground bond tester - chroma

19752 Guardian Ground Bond Tester
AC output: 45A

An instrument dedicated to measuring grounding resistance within the range of 0.1~510mΩ. Supplies highly reliable and stable test results with a built-in resistance compensate function. Its compact form factor and easy to operate features make it ideal for testing in a production line.

Hipot tester analyzer

19032 Guardian Electrical Safety Analyzer
Hipot 5kVac | 6kVdc
AC/DC/IR/GB/LC/Dynamic Function

The 19032 series combines Hipot, Insulation Resistance (IR), Ground Bond (GB), Leakage Current (LC)/AC LC/DC LC and Dynamic Function Tests. Space savings can be up to 50% of production line space, by eliminating multiple safety test instruments. The 19032 increases  efficiency of electrical safety testing during manufacturing and reduces associated labor costs.