Hioki RM3545A-1 Precision Resistance Meter

The Hioki RM3545A series consists of high-precision resistance meters for accurate DC resistance measurements in components and electrical connections. The instruments offer 13 measurement ranges from 1 mΩ to 1200 MΩ, a maximum test current of 1 A and a resolution down to 1 nΩ. They are designed for production, quality control and laboratory applications where small resistance variations can affect component performance and reliability.

Models

• RM3545A-1: High-precision resistance meter for manual and automated measurements. Compatible with external multiplexer systems such as the Hioki SW1001 and SW1002 for multi-channel measurements.
• RM3545A-2: Offers the same measurement performance as the RM3545A-1, with the additional option of installing up to two Z3003 Multiplexer Cards for a total of 20 measurement channels in 4-wire mode. Also supports external multiplexer systems.

Measurement Performance and Functions

Both models feature a 6½-digit display, a basic accuracy of ±0.045% of reading ±0.010% of full scale and a resolution down to 1 nΩ. Measurement times as short as 2.3 ms enable fast measurement sequences in automated testing and production lines.

The instruments require no warm-up time or manual zero adjustment. A contact-check function verifies proper contact between the measurement probes and the device under test, reducing the risk of incorrect readings.

Temperature Compensation and Precision Functions

The RM3545A features a Temperature Compensation (TC) function that corrects measured resistance values to a specified reference temperature. This compensates for the temperature dependence of materials, such as copper conductors, where resistance changes by approximately 0.4% per °C.

Temperature can be measured using the included Z2001 temperature sensor or a compatible external thermometer with analog output. This function is particularly useful for winding resistance measurements, where temperature variations can otherwise affect the comparability of results.

The instruments also feature Offset Voltage Compensation (OVC), which reduces the influence of thermoelectric voltages and internal offset voltages by reversing the measurement current and averaging the results.

A temperature rise function calculates the temperature increase of the device under test based on resistance changes and ambient temperature.

Multiplexer Measurements

Both models can be combined with the Hioki SW1002 Multiplexer System for automated resistance measurements on up to 132 channels in 4-wire mode.

The RM3545A-2 additionally supports an integrated multiplexer option. Up to two Z3003 Multiplexer Cards can be installed, each providing ten measurement channels in 4-wire mode. This enables automated measurements on up to 20 channels without requiring a separate multiplexer system.

The Z3003 cards can be installed later, allowing users to start with single-channel measurements and subsequently expand the instrument for automated multi-channel testing.

System Integration and Communication

The RM3545A features LAN, USB and RS-232C interfaces for communication with computers and control systems. The EXT I/O interface supports external triggering and pass/fail control in automated test systems.

An analog D/A output of 0–1.5 V DC enables monitoring and control. The command-monitor function displays communication commands and responses directly on the instrument's display, simplifying troubleshooting during system integration.

Applications

• Resistance measurement of busbars and welded joints in battery modules
• Winding resistance measurement in motors and transformers
• Contact resistance testing of EV charging connectors
• Resistance measurement of PCB traces
• Testing high-current components such as fuses and shunt resistors
• Automated resistance measurement in production and quality control
• Technical Specifications
• Measurement function: DC resistance
• Number of measurement ranges: 13
• Resistance range: 1 mΩ to 1200 MΩ
• Basic accuracy: ±0.045% of reading ±0.010% of full scale (1 mΩ range)
• Resolution: Down to 1 nΩ
• Maximum test current: 1 A
• Measurement time: Down to 2.3 ms (10 Ω range, FAST mode)
• Display: 6½ digits
• Temperature compensation: TC
• Offset voltage compensation: OVC
• Temperature rise function: Yes
• Contact check: Yes
• Communication: LAN, USB and RS-232C
• External control: EXT I/O
• Analog output: D/A, 0–1.5 V DC
• External multiplexer systems: Hioki SW1001 and SW1002
• Integrated multiplexer: Up to two Z3003 cards, RM3545A-2 only

Included Accessories

• Power cord
• Z2001 Temperature Sensor
• Male EXT I/O connector
• EXT I/O connector cover
• Spare fuse (F1.6AH 250 V)
• Start-up guide
• Operating precautions
• Instruction manual

Note: Z3003 Multiplexer Cards, external multiplexer systems and measurement leads are not included in the standard delivery according to the supplied accessory lists.