RM-26999 Specifications

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Updated2025-06-25
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RM-26999 Specifications

These specifications apply to the RM-26999.

All specifications are subject to change without notice.

Notice The protection provided by the RM-26999 can be impaired if it is used in a manner not described in this document.

Definitions

Warranted specifications describe the performance of a model under stated operating conditions and are covered by the model warranty.

Characteristics describe values that are relevant to the use of the model under stated operating conditions but are not covered by the model warranty.

Typical specifications describe the performance met by a majority of models.
Nominal specifications describe an attribute that is based on design, conformance testing, or supplemental testing.

Specifications are Typical unless otherwise noted.

Current Transducer Calibration Port (Cal Input) Pinout

This 9-pin DSUB port allows you to calibrate current transducers with calibration windings that are connected to the RM-26999.

The Current Transducer Calibration Port routes to each of the four current transducer ports.

Figure 1. Current Transducer Calibration Port

Table 1. Current Transducer Calibration Port Signal Descriptions
Pin	Description
1	Transducer 3, calibration winding +
2	Transducer 2, calibration winding +
3	Transducer 1, calibration winding +
4	Transducer 0, calibration winding +
5	Ground reference
6	Transducer 3, calibration winding -
7	Transducer 2, calibration winding -
8	Transducer 1, calibration winding -
9	Transducer 0, calibration winding -

RM-26999 Current Transducer Port Pinout

The RM-26999 does not directly measure current. Use a current transducer to measure current. The 9-pin DSUB Current Transducer Ports on the device are optimized for flux-gate transducers by providing all the necessary power, communication, and signal lines.

Table 2. Current Transducer Ports
Port	Signal	NI-DAQmx Channel
Current 0	AI4	MIODevice/ai4
Current 1	AI5	MIODevice/ai5
Current 2	AI6	MIODevice/ai6
Current 3	AI7	MIODevice/ai7

Figure 2. Current Transducer Port Pinout

Table 3. Current Transducer Port Signal Descriptions
Pin	Description
1	AI- channel input, ±10 V signal
2	Calibration winding -
3	Transducer status ground
4	Transducer supply ground return, ±2.25 A maximum
5	-15 V transducer supply output, ±5%, no load, 2.25 A maximum
6	AI+ channel input, ±10 V signal
7	Calibration winding +
8	Transducer status, 5 V, 10 mA maximum
9	+15 V transducer supply output, ±5%, no load, 2.25 A maximum

Note The RM-26999 allows you to calibrate your current transducers, if necessary for your system. Consult your transducer documentation to verify that your transducer supports calibration through windings.

Conditions

Specifications are valid for the range 0 °C to 55 °C unless otherwise noted.

These specifications are for the RM-26999. Accuracy for the entire system must be calculated including both the RM-26999 accuracy and the DAQ device accuracy.

Voltage Input Characteristics

Input voltage, maximum

1,000 V, Category II

2,000 V peak, other, non-MAINs circuits

Number of channels

Table 4. Signal Accuracy, 2,000 V Range
Signal Frequency	Accuracy^[1]¹ T_cal ±5 °C. Accuracy is valid after offset compensation.^,^[2]² Voltages that exceed 750 V from 30 kHz to 100 kHz or 220 V above 100 kHz are for reference only.
Signal Frequency	Typical-95	Warranted
DC	±0.05% of reading	±0.05% of reading
1 Hz to 500 Hz	±0.08% of reading	±0.1% of reading
>500 Hz to 1 kHz	±0.1% of reading	±0.2% of reading
>1 kHz to 5 kHz	±0.25% of reading	±0.9% of reading
>5 kHz to 10 kHz	±0.3% of reading	±1.15% of reading
>10 kHz to 200 kHz	±0.4% of reading	±1.35% of reading
>200 kHz to 1 MHz	±(0.004 × signal frequency in kHz)% of reading	±(0.014 × signal frequency in kHz)% of reading

System noise^[3]³ The system noise specifications are representative values to help understand the expected quality of the measurement. A PXIe-6366 and RM-26999 were used to create this representative list.
±2,000 V range	53 mV RMS
±1,000 V range	31 mV RMS
±400 V range	22 mV RMS
±200 V range	21 mV RMS

DC offset^[4]⁴ The DC offset specification is in reference to output voltage.

2 mV

Noise contribution, 5 MHz bandwidth^[5]⁵ Noise contribution is referred to input (RTI) and is scaled up to account for the RM-26999 attenuation.

13 mV RMS, RTI

T_cal^[6]⁶ T_cal = temperature at which last external calibration was performed.

23 °C ± 5 °C

Calibration interval

2 years

Gain drift

±25 ppm/°C

Attenuation

200:1

CMRR

>100 dB DC, typical

Long-term stability

125 p p m / \sqrt{1, 000 h r s}

Input impedance, single-ended to earth

10 MΩ || 4.7 pF

-3 dB bandwidth

1 MHz

Output impedance

50 Ω

Current Input Characteristics

Note Current input characteristics are determined by the connected DAQ devices. For more information about device input characteristics, refer to the device documentation on ni.com/manuals.

Note If you connect a current transducer with current output to the RM-26999, install a shunt to convert the current signal to a voltage signal. Refer to the RM-26999 User Manual on ni.com/manuals for more information about connecting current transducers with current output.

Number of channels	4
DAQ device measurement voltage ranges	±1 V, ±2 V, ±5 V, ±10 V
Burden resistors	0.5 Ω, 1 Ω, 2 Ω, 5 Ω, 10 Ω
Maximum current input	Selectable on the DAQ device
Input protection	Determined by the DAQ device
Shunt accuracy	±0.05%, metal foil, 2 W, maximum
Shunt gain drift	±0.2 ppm/°C

Power Requirements

Voltage input range

24 V DC ± 5%

Maximum power consumption

150 W

Recommended power supply

NI PS-15 (5 A, 120 W)

NI PS-16 (10 A, 240 W)

Physical Characteristics

Dimensions

482.6 mm × 43.9 mm × 156.2 mm

(19.00 in. × 1.73 in. × 6.15 in.)

Weight

3,020 g (106.50 oz)

Safety Voltages

Connect only voltages that are below these limits.

Input voltage range

1,000 V, Category II

2,000 V peak, other, non-MAINs circuits

Channel-to-channel, channel-to-earth

Continuous working voltage

1,000 V, Category II

2,000 V peak, other, non-MAINs circuits

Transient overvoltage

6,000 V peak

Caution Do not connect the RM-26999 to signals or use for measurements within Measurement Categories III or IV. Do not connect to signals or use for measurements above 1,000 V RMS within Measurement Category II.

Attention Ne connectez pas le RM-26999 à des signaux et ne l'utilisez pas pour effectuer des mesures dans les catégories de mesure III ou IV. Ne le connectez pas à des signaux et ne l'utilisez pas pour effectuer des mesures supérieures à 1000 Veff dans la catégorie de mesure II.

Measurement Category II is for measurements performed on circuits directly connected to the electrical distribution system. This category refers to local-level electrical distribution, such as that provided by a standard wall outlet, for example, 115 V for U.S. or 230 V for Europe. Above 1,000 V RMS, these test and measurement circuits are not rated for measurements performed on circuits directly connected to the electrical distribution system referred to as MAINs. MAINs is a hazardous, live electrical supply system to which equipment is designed to be connected to for the purpose of powering equipment. Above 1,000 V RMS, this product is rated for measurements of voltages from specially protected secondary circuits, up to 2,000 V peak. Such voltage measurements include signal levels, special equipment, limited energy parts of equipment, circuits powered by regulated low-voltage sources, and electronics.

Caution Connect the PE terminal to protective earth ground in the rack installation or electrical cabinet.

Attention Connectez le terminal de mise à la terre à la borne correspondante (masse) dans l'installation en rack ou dans l'armoire électrique.

Environmental Characteristics

Temperature and Humidity

Temperature
Operating	0 °C to 55 °C
Storage	-40 °C to 71 °C

Humidity
Operating	10% RH to 90% RH, noncondensing
Storage	5% RH to 95% RH, noncondensing

Pollution Degree

Maximum altitude

2,000 m

Notice This product is intended for use in indoor applications only.

Shock and Vibration

Random vibration
Operating	5 Hz to 500 Hz, 0.3 g RMS
Non-operating	5 Hz to 500 Hz, 2.4 g RMS

Operating shock

30 g, half-sine, 11 ms pulse

¹ T_cal ±5 °C. Accuracy is valid after offset compensation.

² Voltages that exceed 750 V from 30 kHz to 100 kHz or 220 V above 100 kHz are for reference only.

³ The system noise specifications are representative values to help understand the expected quality of the measurement. A PXIe-6366 and RM-26999 were used to create this representative list.

⁴ The DC offset specification is in reference to output voltage.

⁵ Noise contribution is referred to input (RTI) and is scaled up to account for the RM-26999 attenuation.

⁶ T_cal = temperature at which last external calibration was performed.