Azbil NWA300 User manual

OM2-5190-0920
Field-Based Analog
4 - 20mA DC Current Meter
Model NWA300
User's Manual

NOTICE
While the information in this manual is presented in good faith and
believed to be accurate, Azbil Corporation disclaims any implied
warranty of merchantability or fitness for a particular purpose and
makes no express warranty except as may be stated in its written
agreement with and for its customer.
In no event shall Azbil Corporation be liable to anyone for any indirect,
special or consequential damages. is information and specications
in this document are subject to change without notice.
© 1994-2020 Azbil Corporation. All Rights Reserved.

i
Table of Contents
General Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Chapter 1. Configuration And Structure Of NWA Current Indication System . . . . . . . . .2
1-1. System Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1-2. Notes on the Explosion-proof NWA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1-3. Structure and Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Main Unit Indicator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Terminal Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Chapter 2. Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2-1. Before Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Mounting Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2-2. Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
2-3. Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Wiring when only one NWA is used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Wiring when multiple NWAs are used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Wiring for the pressure-resistant, explosion-proof model . . . . . . . . . . . . . . . . . . . . . . . .19
Chapter 3. NWA Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3-1. Start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

1
General Precautions
Checking the Product
e NWA is a precision instrument. When unpacking the unit, handle all materials
carefully to prevent accident or damage.
Conrm that you have received the following items:
– NWA main unit
– Standard accessories
Checking the Specications
The specifications of the NWA meter are inscribed on the nameplate. Make sure
that the specifications are correct, referencing the appendix “Indication Of NWA
Standard Specications And Tag No.”.
Pay special attention to the following two items:
– Structure of the main unit
– Scale type
Inquiries
If you find errors in the specification, or have any questions regarding the
specications, please contact the azbil Group sales oce.
In this case be sure to inform us of the NWA Tag and Product Numbers.
Notes on Storage
When storing the NWA before installation, pay attention to the following:
– Store it indoors in a place with constant room temperature and humidity, and
where it is not subject to vibration or shock.
– Store it as originally packed.

2
Chapter 1. Configuration And Structure Of NWA Current
Indication System
Overview
This chapter introduces the configuration of the NWA current indication system, and
includes:
– The structure of the NWA main unit, with the names and functions of each section.
– Notes regarding use of the explosion-proof NWA.
1-1. System Configuration
Overview
The NWA analog meter displays analog DC signals in the 4 to 20 mA range, obtained from
various field instruments.
Current Indication Using the NWA
The following shows the configuration of a typical current indication system using the NWA.
Fig. 1-1. Configuration of the NWA Current Indication System

3
1-2. Notes on the Explosion-proof NWA
Overview
The NWA explosion-proof model is certified to comply with Japan’s Industrial Safety and
Health Laws, and can thus be used in dangerous locations. For proper use, the following
guidelines must be followed.
Pressure-Resistant, Explosion-proof Structure
The pressure-resistant and explosion-proof structure is totally sealed, which contains possible
internal explosions, and prevents ignition of external explosive gases.
Selection of Mounting Location
When selecting a mounting location for the NWA, observe the following conditions:
– Dangerous locations in which the NWA can be safely installed are defined as follows:
Gases classed as requiring explosion-
proof instruments
Atmospheres with a flashpoint of 85C or
higher
The NWA analog meter can be installed in Type 1 or 2 locations; it cannot be installed in
Type 0 locations.

4
Installation
– When installing the NWA, in either dangerous or nondangerous locations, always refer to
the Appendix “Installation Specifications” to confirm correct wiring.
– Perform all external wiring following the cable installation procedures given in the
document “Recommended Practice for Explosion-Protected Installations in General
Industries”, published by Japan’s Ministry of Labor’s Research Institute for Industrial Safety.
For cable installation, be sure to attach the standard Azbil Corporation pressure-resistant
packing cable adapter to the wiring port of the terminal box.
– The explosion-proof properties of the pressure-resistant explosion-proof structure are
maintained by the length of the flamepath, gap, and by the mechanical strength of the
casing. Therefore, make sure that there is no corrosion, distortion, or scarring of the case
cover, any of which may cause reduced mechanical strength. Handle the meter carefully to
avoid damage to screws and joints.
If any of the above conditions is not satisfied, the NWA’s explosion-proofing cannot be
guaranteed.
Install and use the NWA only under the proper conditions. If the NWA becomes damaged,
contact the azbil Group sales office.
Nameplate
The NWA explosion-proof model is certified to comply with Japan’s Industrial Safety and
Health Laws for use in dangerous locations. A certification mark is attached to the nameplate
of explosion-proof products, as shown below. Check that mark is present.
Fig. 1-2. Nameplate

5
1-3. Structure and Function
Structure
Major components
The NWA analog meter consists of the main unit indicator and the terminal box, as shown
below.
Fig. 1-3. General View of the NWA

6
Names and Functions of each Section
The following table shows the name and function of each section of the NWA.
<Name> <Function>
Main unit indicator Receives analog signal from the transmitter and
indicates values
Terminal box Accommodates input signal terminals
Fastening screw for explosion-
proofing
For explosion-proof model, be sure to fasten this screw
when in use
Nameplate The Model No. and Product No. are inscribed, and the
explosion-proofing certification seal is stamped
Pressure-resistant packing cable
adapter
Seals the cable terminals to maintain explosion-proofing
and improve insulation properties and mechanical
strength. This adapter is required for explosion-proof
instrumentation. See Fig. 1-4 and Fig. 1-5.
External grounding terminal Connect the ground lead from this terminal to a good
ground as close as possible to the unit, Be sure to use
signal point (Type 3) grounding.
Caution: The NWA analog meter may not operate
normally without proper grounding.

7
Fig. 1-4. General View of the Pressure-Resistant Packing Cable Adapter
Fig. 1-5. Assemblies of the Pressure-Resistant Packing Cable Adapter

8
Main Unit Indicator
Description
The functions and structure of the main unit indicator are as follows:
– Receives analog signal from the transmitter and indicates values
Name of each Section
The following shows the name of each section of the main unit indicator.
Fig. 1-6. Main Unit Indicator Detail
Function of each section
The following table shows the function of each section of the main unit indicator.
<Name> <Function>
Indicator Incorporates 240 ° meter

9
Terminal Box
Description
The terminal box is provided with output signal terminals.
Name of section
The following shows the name of each section of the terminal box.
Fig. 1-7. Terminal Box Detail

10
Function of each section
The following table shows the function of each section of the terminal box:
<Name> <Function>
Input signal terminal M+ or M- is indicated.
Unconnected terminals These terminals are not normally used. They are used
as relay terminals when multiple NWA meters are
connected. See the subsection “Electrical Installation
(4)” on page 19.
Internal grounding terminal – If the NWA meter is not immune to electrical noise,
connect one end of the shield wire to this terminal.
(Not normally used)
– This terminal is internally connected to the external
grounding terminal. When this terminal is used, make
sure that two-point grounding is not made.

11
Chapter 2. Installation
Overview
This chapter covers the mounting and the electrical installation procedures for the NWA
meter, which differ according to whether or not the transmitter is provided with an output
terminal for external meters, and to whether one or multiple NWAs are used.
It covers:
– Selection of mounting location
– Mounting procedure
– Wiring procedure
– Notes on wiring the pressure-resistant explosion-proof model
2-1. Before Installation
Mounting Environment
Overview
To assure the long-term performance and reliability of the NWA, select the mounting location
according to the following criteria:
Environmental conditions
– Install the meter in a location with ambient temperatures within -10 to +60 °C and ambient
humidity within 5 to 100 % RH, and which is not subject to rapid temperature or humidity
changes.
– Avoid installing the meter near large-current cables, motors, or transformers that might
cause electromagnetic interference.
– Avoid installing the meter in locations subject to excessive vibration or shock, or locations
where corrosive gas may be present.
– Avoid installing the meter in locations exposed to direct sunlight or inclement weather.
– Perform all wiring (in either dangerous or non-dangerous locations) with reference to the
Appendix “Installation Specifications”.
– When installing the meter in dangerous locations, ensure that wiring work also meets the
requirements of Section 1-2. Notes on the Explosion-proof NWA.

12
2-2. Installation
Mounting
Procedure
Follow the steps below:
Step Procedure
1Attach the bracket using the four bracket mounting holes at the back of the
main unit. (See Fig. 2-1.)
2Using the mounted bracket, secure the main unit to the 2B pipe vertically or
horizontally with a U bolt. (See Fig. 2-2.)
Notes: Make sure that the 2B pipe is fixed securely.
Figure
Fig. 2-1 shows the bracket mounting holes. Fig. 2-2 shows the NWA meter mounted on a 2B
pipe.
Fig. 2-1. Rear of the NWA

13
Fig. 2-2. NWA Analog Meter Mounted on 2” Pipe

14
2-3. Wiring
Overview
This subsection covers the following items regarding electrical installation of the NWA:
– Cable connection position
– Cable selection and installation
– Wiring procedure
Caution
Avoid connecting the NWA to commercial power. Otherwise, the internal measurement
circuit may be irrevocably damaged.
Connection position
The following shows the terminal block of the terminal box:
Fig. 2-3. Terminal Block

15
Cable selection
Twisted 600 V vinyl sheath lead CVV (JIS C3401) with a cross section of 2 mm2, or equivalent,
is recommended.
For wiring in locations subject to electrical noise, shielded leads are recommended.
The cable is connected to the terminal box through the conduit jointer (G1/2 female screw).
The optimum diameter of the cable is φ11.
For termination, a crimp contact (M4 screw) with insulated sleeve is recommended.
Cable installation
When installing the cable between the NWA and the transmitter, keep the following points in
mind:
– Avoid installing the cable near electrical noise-emitting equipment such as large-current
transformers, motors, or power supplies. Do not lay the cables in trays or ducts with other
power cables.
– To protect the NWA from water, it is recommended that wiring be performed using conduit
tubes and ducts. Use water-proof glands at conduit joints.

16
Wiring when only one NWA is used
When the transmitter is provided with an output signal terminal for external meters
<Case 1>
Notes: Don’t remove a jumper board on the terminal board (M+ and M-).
<Case 2>
Notes: Don’t remove a jumper board on the terminal board (M+ and M-).