Leak Current Measurement, an Essential Part of Electrical Safety (for electrical devices)

To ensure the safe use of electrical products, electrical safety tests such as insulation resistance, withstand voltage, ground resistance, and leakage current must always be conducted. Hioki Leakage Current Testers comply with laws and standards regarding medical electrical equipment as well as non-medical electrical equipment, and can be used to measure leakage current in all types of electrical products from computers to medical equipment. The ST5541 provides support for standard-compliant networks (excluding medical-use electrical devices). Key Features • Compliance with Electrical Appliances and Materials Safety Act, JIS/IEC/UL standards • Uninterrupted polarity switching function dramatically reduces cycle time • Support for rated currents up to 20 A gives the instrument more than adequate capability for testing products designed to comply with new standards • Touch panel features simple, interactive operation • Communications functionality and external I/O support allow automatic testing on production lines

Model No. (Order Code)

ST5541 For electrical devices

Note: For applications involving leak current measurement of medical-use electrical devices, use the ST5540.


For Standard- and Regulation-compliance Measurement of General-use Electrical Devices

There are various standards in place concerning networks (body simulated resistance), and a standard-compliant network is required in order to make measurements. ST5541 provides standard support for standard-compliant networks (excluding medical-use electrical devices).

3157 Safety Standard for Hospital Electrical Equipment JIS T 1022:2006 Measurement

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 and ST5541. •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.

Basic specifications (Accuracy guaranteed for 1 year, Post-adjustment accuracy guaranteed for 1 year)

Measurement methodsMeasurement of voltage drop across body simulated resistance points, Calculation and display of current values, True rms measurement, Measurement unit floats relative to instrument ground.
Measurement modesLeak current measurement, voltage measurement, safety conductor current measurement
Standards compliance (NW: Body simulated resistance)[NW-A] • Electrical Appliances and Materials Safety Act
• Measurement of touch current and protective conductor current: IEC 60990:2016
• Electrical equipment for measurement, control, and laboratory use: IEC 61010-1:2010+ A1:2016
• Information technology equipment: IEC60950-1:2005+ A1:2009+ A2:2013
• Audio, video and similar electronic apparatus: IEC 60065:2014
• Personnel Protection Systems for EV: UL 2231-1:2012 (Amended 2016), UL-2231-2:2012 (Amended 2016)
[NW-D] • For UL: UL 1492:1996 (Amended 2013)
[NW-G] • Electrical equipment for measurement, control, and laboratory use; current measurement circuits in damp conditions: IEC 61010-1:2010+ A1:2016
Leak current measurementGround leak current, 3 types of contact current, free current measurement, 3 types of enclosure leak current
Measurement currentDC, AC (true rms, 15 Hz to 1 MHz), AC+DC (true rms, 15 Hz to 1 MHz), AC peak (15 Hz to 1 MHz)
Measurement rangesDC / AC / AC+DC mode: 50.00 mA/ 5.000 mA/ 500.0 μA/ 50.00 μA
AC peak mode: 75.0 mA/ 10.00 mA/ 1.000 mA/ 500.0 μA
Measurement accuracy (current measurement)DC measurement: ±2.0% rdg. ±6 dgt. (typ.)
AC / AC+DC measurement: ±2.0% rdg. ±6 dgt. (15 Hz to 100 kHz, typ.)
AC peak measurement: ±2.0% rdg. ±6 dgt. (15 Hz to 10 kHz, typ.)
InterfacesExternal I/O, USB 1.1 (communications), RS-232C
FunctionalityAutomatic test, data storage for 100 target devices, clock, data backup, printed output (optional), etc.
Power supply100/120/220/240 V AC (specify at time of order), 50/60 Hz, 30 VA rated power
Target device power supply input100 to 250 V AC, 50/60 Hz, Rated current input from terminal block: 20 A
Target device power supply outputOutput from terminal block: 20 A, Output from outlet: 15 A
Dimensions and mass320 mm (12.60 in) W × 110 mm (4.33 in) H × 253 mm (9.96 in) D, 4.5 kg (158.7 oz)
AccessoriesTest lead L2200 (Red ×1, Black ×1) ×1 set, Enclosure probe 9195 ×1, Power cord ×3, Spare fuse for measurement line ×1, Instruction manual ×1, User guide ×1, CD-ROM ×1

■ ST5540, ST5541 List of functions (Network)

Network A (Electrical Appliances and Materials Safety Act)
Network B (Medical-use electrical devices)-
Network C (IEC 60990)
Network D (UL)
Network E (General-purpose 1)
Network F (General-purpose 2)
Network G (IEC 61010-1)

■ List of functions (Major functions)

Power on polarity switching function
Rated current 20 A
Function for checking for blown fuses
Frequency band switching-
110% voltage output terminal (T3 terminal)-
S10, S12, S13, E terminal-

■ List of functions (Testing leakage current mode)

Earth leakage current
Touch current
Patient auxiliary current-
Patient leakage current-
Total patient leakage current-
Free current
Enclosure - Earth leakage current
Enclosure - Enclosure leakage current
Enclosure - Line leakage current
Patient leakage current I-
Patient leakage current II-
Patient leakage current III-

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Seminar Videos On Demand

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Seminar Schedule

Power Electronics, Machines and Drives - Online Conference

Dec 15, 2020 - Dec 17, 2020


Catalog: LEAK CURRENT HiTESTER ST5540, ST5541 Download PDF  [2MB] English

User Guides

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If you can not download, log into your myHioki account to access more technical documents and information where available.

Instruction Manual English
Instruction Manual Simplified Chinese
Instruction Manual Korean

Outline Drawings

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Technical Notes

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Declaration of Conformity



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Test probes

*The L2200 and the 9195 are bundled


For the ST5540 series, 3156/3155


70 cm (2.30ft) length, detachable large alligator clips or needle tips are bundled, CAT IV 600V, CAT III 1000V

Printer options


112 mm (4.41 in) × 25 m (82.03 ft), 10 rolls/set


For printing numerical values 112 mm (4.41 in) paper width, not CE marked

AC ADAPTER 9443-02

For the Printer 9442, EU type


9 pin - 9 pin straight, 1.5 m (4.92 ft) length

PC communications

RS-232C CABLE 9637

9 pin - 9 pin, cross, 1.8 m (5.91 ft) length



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