National Instruments NI 9242 User manual

USER MANUAL AND SPECIFICATIONS
NI 9242
4-Channel, 250 Vrms, 24-Bit Simultaneous Analog
Input Module
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2|ni.com |NI 9242 User Manual and Specifications
This document describes how to use the National Instruments 9242
and includes specifications and pin assignments for the NI 9242.
Note The safety guidelines and specifications in this
document are specific to the NI 9242. The other
components in the system might not meet the same safety
ratings and specifications. Refer to the documentation for
each component in the system to determine the safety
ratings and specifications for the entire system.
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NI 9242 User Manual and Specifications |© National Instruments |3
Safety Guidelines
Operate the NI 9242 only as described in this manual.
Hot Surface This icon denotes that the component may
be hot. Touching this component may result in bodily
injury.
Warning This icon denotes a warning advising you to
take precautions to avoid electrical shock.
Caution Do not operate the NI 9242 in a manner not
specified in this manual. Product misuse can result in a
hazard. You can compromise the safety protection built
into the product if the product is damaged in any way. If
the product is damaged, return it to National Instruments
for repair.

4|ni.com |NI 9242 User Manual and Specifications
Safety Guidelines for Hazardous Voltages
If hazardous voltages are connected to the module, take the
following precautions. A hazardous voltage is a voltage greater
than 42.4 Vpk or 60 VDC to earth ground.
Caution Ensure that hazardous voltage wiring is
performed only by qualified personnel adhering to local
electrical standards.
Caution Do not mix hazardous voltage circuits and
human-accessible circuits on the same module.
Caution Make sure that devices and circuits connected
to the module are properly insulated from human contact.
Caution When module terminals are hazardous voltage
LIVE (>42.4Vpk/60 VDC), you must ensure that devices
and circuits connected to the module are properly
insulated from human contact. You must use the NI 9967
connector backshell kit to ensure that the terminals are
not accessible.

NI 9242 User Manual and Specifications |© National Instruments |5
Figure 1 shows the NI 9967 connector backshell.
Figure 1. NI 9967 Connector Backshell

6|ni.com |NI 9242 User Manual and Specifications
Safety Guidelines for Hazardous Locations
The NI 9242 is suitable for use in Class I, Division 2, Groups A, B,
C, D, T4 hazardous locations; Class I, Zone 2, AEx nA IIC T4, and
Ex nA IIC T4 hazardous locations; and nonhazardous locations
only. Follow these guidelines if you are installing the NI 9242 in a
potentially explosive environment. Not following these guidelines
may result in serious injury or death.
Caution Do not disconnect I/O-side wires or connectors
unless power has been switched off or the area is known
to be nonhazardous.
Caution Do not remove modules unless power has been
switched off or the area is known to be nonhazardous.
Caution Substitution of components may impair
suitability for Class I, Division 2.
Caution For Division 2 and Zone 2 applications, install
the system in an enclosure rated to at least IP 54 as
defined by IEC/EN 60529.

NI 9242 User Manual and Specifications |© National Instruments |7
Special Conditions for Hazardous Locations Use in
Europe
This equipment has been evaluated as Ex nA IIC T4 Gc equipment
under DEMKO 12 ATEX 1202658X. Each module is marked
II 3G and is suitable for use in Zone 2 hazardous locations, in
ambient temperatures of -40 °C ≤Ta ≤70 °C. If you are using the
NI 9242 in Gas Group IIC hazardous locations, you must use the
device in an NI chassis that has been evaluated as Ex nC IIC T4,
EEx nC IIC T4, Ex nA IIC T4, or Ex nL IIC T4 equipment.
Caution The system shall be mounted in an ATEX
certified enclosure with a minimum ingress protection rating
of at least IP54 as defined in IEC/EN 60529 and used in an
environment of not more than Pollution Degree 2.
Caution The enclosure must have a door or cover
accessible only by the use of a tool.

8|ni.com |NI 9242 User Manual and Specifications
Electromagnetic Compatibility Guidelines
This product was tested and complies with the regulatory
requirements and limits for electromagnetic compatibility (EMC)
as stated in the product specifications. These requirements and
limits are designed to provide reasonable protection against
harmful interference when the product is operated in its intended
operational electromagnetic environment.
This product is intended for use in industrial locations. There is no
guarantee that harmful interference will not occur in a particular
installation, when the product is connected to a test object, or if the
product is used in residential areas. To minimize the potential for
the product to cause interference to radio and television reception
or to experience unacceptable performance degradation, install and
use this product in strict accordance with the instructions in the
product documentation.
Furthermore, any changes or modifications to the product not
expressly approved by National Instruments could void your
authority to operate it under your local regulatory rules.

NI 9242 User Manual and Specifications |© National Instruments |9
Special Guidelines for Marine Applications
Some products are Lloyd’s Register (LR) Type Approved for
marine (shipboard) applications. To verify Lloyd’s Register
certification for a product, visit ni.com/certification and
search for the LR certificate, or look for the Lloyd’s Register mark
on the product label.
Caution In order to meet the EMC requirements for
marine applications, install the product in a shielded
enclosure with shielded and/or filtered power and
input/output ports. In addition, take precautions when
designing, selecting, and installing measurement probes
and cables to ensure that the desired EMC performance is
attained.

10 |ni.com |NI 9242 User Manual and Specifications
Connecting the NI 9242
The NI 9242 provides connections for four analog input channels.
Figure 2. NI 9242 Pinout
AI0
AI1
AI2
Neutral
0
1
2
3

NI 9242 User Manual and Specifications |© National Instruments |11
Connector
The NI 9242 has a 4-terminal, detachable screw-terminal
connector.
Backshell
Caution For safe operation with hazardous voltages,
you must use the NI 9967 Connector Backshell, as shown
in Figure 1, with the 4-terminal connector on the NI 9242.
You can use the backshell with 12 AWG to 24 AWG wires with the
NI 9967. 12 AWG to 14 AWG, 16 AWG, and 18 AWG to 24 AWG
require different strain-relief pieces.

12 |ni.com |NI 9242 User Manual and Specifications
Installing the NI 9967 Using 12 AWG to 14 AWG Wire
Complete the following steps to install the NI 9967 using 12 AWG
to 14 AWG wires.
Figure 3. 12 AWG to 14 AWG Installation
1 Route wires over the strain-relief piece.
2 Secure strain-relief piece and NI 9967 backshell in place using captive
screws.
1
2

NI 9242 User Manual and Specifications |© National Instruments |13
Installing the NI 9967 Using 16 AWG Wire
Complete the following steps to install the NI 9967 using 16 AWG
wires.
Figure 4. 16 AWG Installation
1 Route wires through the strain-relief pieces.
2 Secure strain-relief piece and NI 9967 backshell in place using captive
screws.
1
2

14 |ni.com |NI 9242 User Manual and Specifications
Installing the NI 9967 Using 18 AWG to 24 AWG Wire
Complete the following steps to install the NI 9967 using 16 AWG
wires.
Figure 5. 18 AWG to 24 AWG Installation
1 Route wires over the strain-relief piece.
2 Secure strain-relief piece and NI 9967 backshell in place using captive
screws.
1
2

NI 9242 User Manual and Specifications |© National Instruments |15
Signals
The NI 9242 has three AI terminals and a Neutral terminal. You
can connect three-phase and single-phase measurement
configurations to the NI 9242. The NI 9242 supports standard
service levels up to 250 Vrms Line-to-Neutral (L-N) and 400 Vrms
Line-to-Line (L-L). You can also connect standard potential
transformers to the NI 9242.
Note You must use 2-wire ferrules to create a secure
connection when connecting more than one wire to a
single terminal on the NI 9242.
Circuitry
Each channel on the NI 9242 provides an independent signal path
and ADC. Each terminal has the same input impedance to ground.
The NI 9242 returns the voltage between each AI terminal and the
Neutral terminal as well as the voltage between the Neutral
terminal and the chassis ground. Refer to Figure 6 for a diagram of
the equivalent voltages the module returns.

16 |ni.com |NI 9242 User Manual and Specifications
Figure 6. Internal Circuitry for the NI 9242
To ensure that measurements to chassis ground are correct, NI
recommends connecting the chassis to earth ground using the
chassis grounding screw. Refer to your chassis manual for
information about connecting the chassis to earth ground.
NI 9242
AI1
AI2
Neutral
GND
Neutral
AI0
AI1
AI2
AI0
V
V
V
V

NI 9242 User Manual and Specifications |© National Instruments |17
Connecting Phase Measurements
You can connect three-phase measurement configurations and
single-phase measurement configurations to the NI 9242.
NI recommends using the following phase measurement
configurations for typical power distribution networks. Other valid
configurations are possible if the connections do not exceed the
safety rating of the NI 9242.

18 |ni.com |NI 9242 User Manual and Specifications
Connecting Three-Phase Measurement
Configurations
You can connect WYE or delta measurement configurations to the
NI 9242.
Figure 7. Connecting a 4-Wire WYE Measurement Configuration
NI 9242
AI0
Phase A
Phase B
Phase C
NeutralNeutral
AI2
AI1

NI 9242 User Manual and Specifications |© National Instruments |19
Figure 8. Connecting a High-Leg Delta Measurement Configuration
NI 9242
AI0
Phase A
Phase B
Phase C
Neutral
AI2
AI1
Neutral

20 |ni.com |NI 9242 User Manual and Specifications
Figure 9. Connecting a 3-Wire Delta Measurement Configuration
NI 9242
AI0
Phase A
Phase B
Phase C AI2
AI1