Yokogawa EJA118 - Manual (Page 64)

EX-A03E 1
INSTALLATION AND OPERATING PRECAUTIONS FOR JIS INTRINSICALLY SAFE EQUIPMENT
INSTALLATION AND OPERATING PRECAUTIONS FOR
JIS INTRINSICALLY SAFE EQUIPMENT
Apparatus Certified Under Technical Criteria (IEC-compatible Standards)
and from “RECOMMENDED PRACTICES for Explosion-Protected Electri-
cal Installations in General Industries,” published in 1979
1. General
The following describes precautions on electrical apparatus
of intrinsically safe construction (hereinafter referred to as
intrinsically safe apparatus).
Following the Labor Safety and Health Laws of Japan, an
intrinsically safe apparatus must undergo type tests in order
to be certified by the Technical Institute of Industrial Safety,
Inc. These tests are required to satisfy either the technical
criteria for electrical machinery and equipment in compliance
with explosionproof standards involving inflammable gases
or vapors and for machinery and equipment having
explosionproof performance (standards notification no. 556
from the Japanese Ministry of Labor) (hereinafter referred to
as technical criteria), in conformity with IEC Standards, or
the “Recommended Practice for Explosion-Protected
Electrical Installations in General Industries,” published in
1979. Such a certified apparatus can be used in hazardous
locations where inflammable gases or vapors may be present.
Certified apparatus includes a certification label and an
equipment nameplate with the specifications necessary for
explosion requirements as well as precautions on explosion
protection. Please confirm these precautionary items and use
them to meet specification requirements.
For electrical wiring and maintenance servicing, please refer
to “Internal Wiring Rules” in the Electrical Installation
Technical Standards as well as “USER’S GUIDELINES for
Electrical Installations for Explosive Gas Atmospheres in
General Industry,” published in 1994.
To meet intrinsically safe requirements, equipment that can
be termed an “intrinsically safe apparatus” must:
(1) be certified by the Technical Institute of Industrial
Safety, Inc. in accordance with the Labor Safety and
Health Laws of Japan and have the appropriate mark of
certification labeled on its case, and
(2) be used in compliance with the specifications marked on
its certification label, equipment nameplate and
precautionary information furnished.
Note: Intrinsically safe apparatus satisfy their performance under
specific conditions. They are not always absolutely safe under
every operational and environmental condition. In other
words, they are not safe products involved with factors such
as chemical reactions, geographical changes or the like other
than affected by electric energy from the equipment itself.
2. Electrical Apparatus of Intrinsic
Safety Type of Explosion-
Protected Construction
The intrinsic safety type of explosion-protected construction
is a method of protection applicable to a circuit or part of a
circuit in which, under prescribed test conditions, no spark or
thermal effect, whether produced normally or accidentally, is
capable of causing a prescribed explosive gas to ignite. In
other words, electrical apparatus of this construction is
intended to suppress electrical energy thereby preventing
ignition of a given explosive gas atmosphere even though
spark or high thermal effect occurs in the electric circuitry.
Intrinsically safe electrical apparatus generally comprise
intrinsically safe apparatus installed in a hazardous location
and a safety barrier (associated apparatus), installed in a non-
hazardous location, aimed at preventing electrical energy
from flowing into the electric circuitry of intrinsically safe
apparatus.
However, battery-operated, portable intrinsically safe
apparatus or the like may be used alone.
3. Terminology
(1) Intrinsically safe apparatus: Electrical apparatus in which
all the circuits are intrinsically safe circuits.
(2) Associated apparatus: Electrical apparatus in which there
are both intrinsically safe circuits and non-intrinsically
safe circuits that can affect the safety of intrinsically safe
circuits.
(3) Safety barrier: A specific type of associated apparatus,
which consists mainly of safety barrier elements, and
serves to limit the flow of excessive electrical energy,
which is capable of causing ignition of a given explosive
gas or vapour of a non-intrinsically safe circuit into
concerned intrinsically safe circuits.
(4) Apparatus of category “ia”: Intrinsically safe electrical
apparatus and associated apparatus which are incapable
of causing ignition of a given explosive gas or vapour
with the appropriate safety factors such as: