PT2E-1680

Gas Detector
GD-70D-NT Series

System Construction Manual

RIKEN KEIKI Co., Ltd.

2-7-6 Azusawa Itabashi-Ku, Tokyo, 174-8744, Japan
Website: http://www.rikenkeiki.co.jp/

Contents
1. Introduction
1-1. Procedures for laying NT communication line ............................................................................. 2

2. Important Notices on Safety
2-1. DANGER, WARNING, CAUTION, and NOTE ............................................................................. 3
2-2. Warnings ..................................................................................................................................... 3

3. NT communication line composition and specifications
3-1. Overview of communication line configurations .......................................................................... 4

4. Model selection
4-1. Device and cable selection ......................................................................................................... 55. System construction
5-1. Important information on design and cabling .............................................................................. 65-2. Gas detector installation and wiring .......................................................................................... 105-3. MDU installation and wiring ...................................................................................................... 165-4. Noise filter specifications and exterior diagram......................................................................... 19

6. Testing and measurement
6-1. Measurement and testing after cabling ..................................................................................... 206-2. Communication test for entire DC power-line network .............................................................. 20

7. Maintenance7-1. Maintenance intervals and maintenance items ......................................................................... 22
7-2. Securing spare parts for emergency response ......................................................................... 22

Appendices
Appendix 1. Checklist for configuration design ................................................................................ 24
Appendix 2. System construction checklist ...................................................................................... 25
Appendix 3. Communication failure checklist ................................................................................... 26
Appendix 4. List of measuring instruments and tools ....................................................................... 27
Appendix 5. Description of terms ..................................................................................................... 2815-4. Noise filter specifications and exterior diagram
Exterior diagram (unit: mm)

Circuit diagram

Ratings
Model
Rated voltage
Rated current
Voltage resistance
Between terminals and case
Insulation resistance
Between terminals and case
Leakage current
Voltage drop
Temperature increase
Operating temperature range

19SUP-B11110-F
250 V DC
10 A
1,500 Vrms 50/60 Hz 60 sec
6,000 MΩ or more (at 500 V DC)
10 μA or less (at 250 Vrms 60Hz)
3.0 Vrms or less
70°C or less
−25 to +50°C

② How to use rate check
Error countNumber of executions (0 to 9999)

１ ＲＡＴＥ ＣＨＥＣＫ Ｎｏ． ３
ＣＮＴ． ［２］ ［１／１００］
ＡＶＥＲＡＧＥ［
１． ５０％ ］
２＞
０＞
０＞
０＞
０

Device no.
(Gas detector)

Error rate(average)
Previous error counts (1 > 2 > 3 > 4 > 5 times
previous)

The rate check displays the error count when 100 pieces of data are transmitted at once.
The judgment criteria for a pass is the number of executions “CNT. [ 3]” (300 times) and the error rate is
5% or less.
When “CNT. [ 3]” is reached, confirm and then press the MODE to exit. Follow [Operation 3. Selectgas detector address] on the previous page to select the next gas detector No. and repeat the ratecheck.
Also check that the maximum error count each time is less than 10.
If the above judgment criteria are exceeded, review wiring, installation location, the earth line,
terminating resistors, etc.

21

Appendix 1. Checklist for configuration design
Listed below are check items before construction:
№Item

1

Power supply
capacity

System design is such that the power supply
capacity is not exceeded even if the maximum
number of gas detectors are connected.
The supply capacity has been added cumulatively
when a pyrolyzer (PLU-70) has been connected.

 OK/ NG

2

Anti-noise measures

The cable route is isolated from noise sources.

 OK/ NG

3

Cable selection

Both RS-485 and DC power-line communication
Shielded twisted pair
・ KPEVS-1.25 mm2-1P, or CPEVS-0.9Φ-1P・ There are not multiple types of cable mixed inthe same communication system OK/ NG4

DC power-line
communication
Communication line
configurations

When only the MDU is separated:
・ The extension distance is MAX. 300 m.

 OK/ NG

When gas detectors are dispersed:
・ There is no more than 300 m of cable distance
between two devices on a communication line.

 OK/ NG

When connected using the multi-drop method:
・ MAX. 30 m
・ Pyrolyzer (PLU-70) has not been connected.

 OK/ NG

When two systems are housed in a single case:・ No contact between 100 V, 24 V, and DC
power-line communication lines
・ No contact between DC power-line
communication lines from different systems

 OK/ NG

One power supply unit is provided for eachindividual DC power-line communication linesystem.

 OK/ NG

RS-485
Communication line
configurations

Uses the multi-drop method with no junctioning.

 OK/ NG

The extension distance is a maximum of 1,200 m.

 OK/ NG

Number of devices
connected

RS-485・ Each system has 16 or fewer MDUs.

 OK/ NG

DC power-line communication
・ Each system has one MDU.
・ Each MDU has 16 or fewer gas detectors.

 OK/ NG5

6

Judgment criteria

24

Judgment/result

Appendix 2. System construction checklist
Listed below are the check items after construction.
№Item

1

Grounding theshielded line in thecommunication line

Grounded OK/ NG

2

DC power-line
communication line
Long distance parallel
cabling

The cables are not laid completely in parallel overextended distances.

 OK/ NG

3

Communication cable
Isolation from noise
sources

The cable is isolated in racks dedicated forcommunication or by separators.

 OK/ NG

The cable is kept away from noise sources.
[Reference]・ From transformers and motors: 120 cm or more・ From AC power cables:
30 cm or more・ From fluorescent lamps:
13 cm or more

 OK/ NG

DC power-line
communication
Terminating resistor

Check to confirm that the fitting and configuration
are correct.

 OK/ NG

When the gas detector has a terminating resistor
・ The gas detector case has been marked.

 OK/ NG

4

Judgment criteria

Judgment/result

See No. 10 in “5-1． Important information on design and cabling.”

5RS-485
Terminating resistor

Check for correct fitting and configuration

 OK/ NG

6Grounding

The gas detector case is grounded.
(Equivalent to Class D grounding) OK/ NG

See No. 9 in “5-1．Important information on design and cabling.”

25

Appendix 3. Communication failure checklist
Listed below are things to check if you encounter communication problems after the host system isstarted.
№1

Item
No communication

Judgment criteria

Judgment/result

Is the communication cable correctly connected?

 OK/ NG

Is the power on?

 OK/ NG

Are any of the devices connected to thecommunication line not part of the system?
・ RS-485
The MDU and upstream device (PLC, etc.) arethe only connected devices.
・ DC power-line communication
Is there a device connected that is unrelated tocommunication?
(For example, the device is connected simply forthe 24 V power supply.)
Excluding the PLU-70 (pyrolyzer unit) OK/ NG

Are the address, communication speed, and otherparameters set correctly?

 OK/ NG

Is the cable connected correctly?

 OK/ NG

Are there any noise sources near the gas
detector?

 OK/ NG

Are there any noise sources near the cable route?

 OK/ NG

Also refer to “Appendix 1. Checklist for configuration design” and “Appendix 2.
System construction checklist” on the previous two pages.

 OK/ NG(Confirm as instructed by the person in charge of thesystem.）

2

Unstablecommunication

26

Appendix 4. List of measuring instruments and tools
Item
Crimping tool

Description
For the terminal plate of the gas detector main unit
Crimping the bar terminals
・Manufacturer
WAGO
・ModelVarioCrimp 4 (206-204)
・Bar terminal (ferrule)
Model 216 series

27Appendix 5. Description of terms
Term

Description

DC power-line
communication

This is also called the NT method.
For dedicated communication with the Riken Keiki gas detector
Connected using 1P of twisted-pair cable
To reduce wiring requirements, the same cable supplies power to thegas detectors.

Free topology

This wiring method allows both multi-drop and junction connection
methods.

Multi-drop

Describes a method for connecting across multiple units ofcommunication bases in a series.

CrosstalkInterference
Crosstalk may occur; that is, the signal on shielded twisted pair cable
may affect a signal on another cable resulting in different signals
being mixed and received.

28

Manual Log
Rev.
0Amendment
First issue

Issue data
2019/1/29