9 April 2020 : Inspecting Medical Equipment for Leakage Current – Hioki ST5540

During this global pandemic, the need for medical equipment such as ventilators cannot be overstated, and manufacturers all over the world are rushing to meet the demand. As with most electrical equipment, medical devices must also be tested for safety, especially since the devices often come into direct contact with the patient or healthcare worker.

IEC 60601-1 Ed. 3 is a widely accepted safety standard for medical electrical equipment. Part of the standard addresses patient leakage current, i.e., leakage current that flows through a patient connected to an applied part or parts. The Hioki ST5540 Leak Current HiTester was developed to meet the requirements for this particular testing application. Among the many features, the ST5540:

  • Complies with IEC 60601-1 Ed.3.0:2005, IEC 60601-1 Amd.1 Ed.3.0:2014, and JIS T 0601-1:2017.
  • Provides an uninterrupted-power polarity switching function.
  • Supports current ratings of up to 20 A
  • Can measure protective conductor current
  • Provides an extensive range of check functionality

Leak Current Parameters For Medical-Use Electrical Devices : 

  • Ground Leak Current
  • Contact Current
  • Patient Leak Current
  • Patient Measurement Current

The ST5540 provides a single solution for measuring all these leak current variants.


Complies with IEC 60601-1:2005 +A1:2012 (Ed 3.1)

In order to prevent the danger of electric shock, electrical devices use power supplies that are isolated from parts of the device that may come into contact with the body. However, it is impossible to achieve infinite insulation resistance. Some leak current always exists, and its magnitude changes as the insulation degrades over time. The LEAK CURRENT HiTESTER ST5540 provides an easy-to-operate solution for measuring leak current in electrical devices, making it eminently suitable for use in an extensive array of applications, ranging from production lines to equipment maintenance and inspections.

Comparison of ST5540 Functionality
ST5540 vs General Use Electrical Devices


ST5540 Product Features

  • Compliance with  IEC 60601-1:2005 Ed 3.0 , JIS T 0601-1:2012. 
    (*Starting on June 1, 2012, medical electrical equipment sold in the EU must comply). Model ST5540 comply with IEC 60601-1:2005 +A1:2012 (Ed 3.1), and IEC 62353 of 2017

Model ST5540 comply with. IEC 60601-1:2005+A1:2012(Ed. 3.1), and IEC 62353 of 2017.

Compliance with Electrical Appliances and Materials Safety Act, JIS, IEC, and UL standards for general-use electrical devices.

  • Uninterrupted Polarity Switching Function
    The ability to conduct tests without turning off the power when switching the power supply polarity dramatically reduces cycle times.

The ST5540 can switch polarity without stopping the supply of power to the device under measurement. Old models require that the device under measurement be turned off and then back on again when switching polarity, but ST5540  let you progress smoothly to the next testing process.

  • Support for rated currents of up to 20 A
    Medical devices that incorporate a computer or sophisticated measurement system are becoming increasingly common. Consequently, these devices have increasingly high rated capacities. By increasing the rated capacity of 15A for the previous product (3156) to 20A, Hioki has made it possible to perform leak current testing for a broader range of medical devices.

    • Simple, interactive operation
      The ST5540/ST5541 uses a touch panel that lets you configure settings by touching selections in response to information displayed on the ipanel, keeping operation.
    • Ability to store up to 30 sets of measurement conditions
      The instrument can save and load up to 30 sets of measurement conditions, allowing you to immediately switch between conditions.
    • Save measurement data for 100 devices
      Measurement data (peak values) can be stored in the instrument’s built-in memory. Saved data can be checked on the stored data reference screen after measurement is complete. Data can be stored for up to 100 test targets, with each target being identified by a registered device name and control number. Additionally, the instrument can store a maximum of 2,000 peak value data points. Together, these capabilities eliminate the need to jot down measured values at the measurement site.

  • Improved test reliability – Blown fuse check function
    When measurement starts, the instrument checks for unintentional probe misalignment using of a preconfigured lower limit setting.
  • Safety conductor current measurement function
    The ST5540/ST5541 can perform safety conductor current measurement as defined in standards such as IEC 60990 and IEC 60950-1.
  • Automatic measurement functionality
    Simple operation allows you to switch power supply polarity and automatically make measurements with the target device in the normal and single-fault states, displaying the peak values. You can also set the measurement time and wait time. These capabilities help reduce operation time.
  • Circuit breaker for device under measurement
    The instrument’s workbench-type design features a terminal block and a circuit breaker on the front panel, making it deal for embedding in test lines and simplifying connectivity with the device being measured, even while rack-mounted.
  • 110% voltage application jack
    The instrument’s 110% voltage application jack, which is used during testing of medical devices, outputs the target device line power supply voltage as-is. The polarity can be switched (ST5540 only).

  • Standard USB interface
    The ST5540/ST5541’s standard USB interface simplifies automatic testing on manufacturing lines and in similar installations.
  • Standard RS-232C port
    The ST5540/ST5541’s standard RS-232C port can be used to control the instrument from a computer and to print data using the 9442 printer (option)
  • Separation of the instrument’s power supply and target device lines
    The instrument’s power supply and target device line power supply are separated, helping prevent damage due to the inadvertent input of an incorrect supply voltage. There’s no need to change the ST5540/ST5541’s supply voltage, even if the target device’s supply voltages changes.

  • Printing saved data – Printer 9442 (Sold Separately)
    The optional PRINTER 9442 can be used to print data via the instrument’s RS-232C interface, providing a convenient way to attach a hard copy of test data.
  • Combine with Hioki AC Grounding HiTester 3157 to meet JIS T 1022:2006
    Safety requirements of electrical installations for medically used rooms in hospitals and clinics.
    Measuring between the grounding center and grounding terminal :Verify that the electrical resistance between the medical outlet’s grounding electrode connector or medical ground terminal and medical ground center is less than or equal to 0.1 Ω by applying a current of approximately 25 A with an AC current with a no-load voltage of 6 V or less and measuring the resistance using the voltage droop method. Combination of Instruments for Leak Current Testing and Safety Conductor Testing The following are key parts of any safety inspection of electrical equipment:

    Leak current test: Measure with the ST5540 (medical use and electrical devices) and ST5541 (electrical devices only)

    Safety conductor test (also known as a ground line resistance test or ground conductor test): Measure with the 3157.

    The 3157 can also be used for conducting measurements under the JIS T 1022:2006 safety standard for hospital electrical equipment.

    Download Leak Current HiTester ST5540/ST5541 Product Catalog
    Download ST5540 Userguide