Yokogawa YTA320 - Manual (Page 43)

2
EX-B03E
• Specific cables shall be used as recommended by the
“USER’S GUIDELINES for Electrical Installations for
Explosive Gas Atmospheres in General Industry,” published
in 1994.
• In necessary, appropriate protective pipes (conduit or flexible
pipes), ducts or trays shall be used for preventing the cable
run (outside the cable glands) from damage.
• To prevent explosive atmosphere from being propagated
form Zone 1 or 2 hazardous location to any different
location or non-hazardous location through the protective
pipe or duct, apply sealing of the protective pipes in the
vicinity of individual boundaries, or fill the ducts with sand
appropriately.
• When branch connections of cables, or cable connections
with insulated cables inside the conduit pipes are made,
a flameproof or increased-safety connection box shall be
used. In this case, flameproof or increased-safety cable
glands meeting the type of connection box must be used for
cable connections to the box.
(2) Flameproof Metal Conduit Wiring
• For the flameproof metal conduit wiring or insulated
wires shall be used as recommended by the USER’S
GUIDELINES for Electrical Installations for Explosive Gas
Atmospheres in General Industry, published in 1994.
• For conduit pipes, heavy-gauge steel conduits conforming to
JIS C 8305 Standard shall be used.
• Flameproof sealing fittings shall be used in the vicinity of
the wiring connections, and those fittings shall be filled with
sealing compounds to complete sealing of the apparatus.
In addition, to prevent explosive gases, moisture, or flame
caused by explosion form being propagated through the
conduit, always provide sealing fittings to complete sealing
of the conduit in the following locations:
(a) In the boundaries between the hazardous and non-
hazardous locations.
(b) In the boundaries where there is a different classification
of hazardous location.
• For the connections of the apparatus with a conduit pipe or
its associated accessories, G-type parallel pipe threads (JIS
B 0202) shall be used to provide a minimum of five-thread
engagement to complete tightness. In addition, since these
parallel threads do not have sealing property, non-hardening
sealant such as liquid gaskets shall thus be applied to those
threads for ensuring waterproofness.
• If metal conduits need flexibility, use flameproof flexible
fittings.
6. Maintenance of Flameproof Apparatus
To maintain the flameproof apparatus, do the following. (For
details, see Chapter 10 “MAINTENANCE OF EXPLOSION-
PROTECTED ELECTRICAL INSTALLATION” in the USER’S
GUIDELINES for Electrical Installations for Explosive Gas
Atmospheres in General Industry.)
() Maintenance servicing with the power on.
Flameproof apparatus shall not be maintenance-serviced with
its power turned on. However, in cases where maintenance
servicing is to be conducted with the power turned on, with
the equipment cover removed, always use a gas detector
to check that there is no explosive gas in that location. If it
cannot be checked whether an explosive gas is present or not,
maintenance servicing shall be limited to the following two items:
(a) Visual inspection
Visually inspect the flameproof apparatus, metal conduits,
and cables for damage or corrosion, and other mechanical
and structural defects.
(b) Zero and span adjustments
These adjustments should be made only to the extent that
they can be conducted from the outside without opening the
equipment cover. In doing this, great care must be taken not
to cause mechanical sparks with tools.
(2) Repair
If the flameproof apparatus requires repair, turn off the power
and transport it to a safety (non-hazardous) location. Observe
the following points before attempting to repair the apparatus.
(a) Make only such electrical and mechanical repairs as will
restore the apparatus to its original condition. For the
flameproof apparatus, the gaps and path lengths of joints
and mating surfaces, and mechanical strength of enclosures
are critical factors in explosion protection.
Exercise great care not to damage the joints or shock the
enclosure.
(b) If any damage occurs in threads, joints or mating surfaces,
inspection windows, connections between the transmitter
and terminal box, shrouds or clamps, or external wiring
connections which are essential in flameproofness, contact
Yokogawa Electric Corporation.
CAUTION
Do not attempt to re-process threaded connections or refinish
joints or mating surfaces.
(c) Unless otherwise specified, the electrical circuitry and
internal mechanisms may be repaired by component
replacement, as this will not directly affect the requirements
for flameproof apparatus (however, bear in mind that the
apparatus must always be restored to its original condition).
If you attempt to repair the flameproof apparatus, company-
specified components shall be used.
(d) Before starting to service the apparatus, be sure to check all
parts necessary for retaining the requirements for flameproof
apparatus. For this, check that all screws, bolts, nuts, and
threaded connections have properly been tightened.
(3) Prohibition of specification changes and
modifications
Do not attempt to change specifications or make modifications
involving addition of or changes in external wiring connections.
7. Selection of Cable Entry Devices for Flameproof
Type
IMPORTANT
The cable glands (cable entry devices for flameproof type)
conforming to IEC Standards are certified in combination
with the flameproof apparatus. So, Yokogawa-specified cable
entry devices for flameproof type shall be used to meet this
demand.
References:
(1) Type Certificate Guide for Explosion-Protected Construction
Electrical Machinery and Equipment (relating to Technical
Standards Conforming to International Standards), issued by
the Technical Institution of Industrial Safety, Japan
(2) USER’S GUIDELINES for Electrical Installations for
Explosive Gas Atmospheres in General Industry (1994),
issued by the Japanese Ministry of Labour, the Research
Institute of Industrial Safety.