I-MICN-01.doc
Issue
06
Mar10
6
IOM –
MICRONEX - ZONE 2
FLOODLIGHT (ATEX, Ex n)
that the lampglass is
not damaged.
2. When
de-energised
and left to cool there
should be no significant
sign of internal
moisture. If there are
signs
of
water
ingress, the luminaire
should be opened up,
dried out, and any likely
ingress points
eliminated
by
re-gasketting.
3. Check
the
cable
gland
for tightness and nip up
if necessary.
4.
Check the tightness of
the cover screws and
nip up if necessary.
5.
Clean the lampglass.
(b)
When relamping, check that
the cover gasket has not
softened or become
excessively deformed, if in
doubt replace (see Section 4.0).
3.9
Electrical Fault
Finding and Replacement
The supply must be isolated
before opening the luminaire.
In most instances the faults are
simple, namely loose or broken
connections, unserviceable
lamps or open circuit control
gear. Control gear will not
normally go open circuit unless
it has first over-heated; the
signs of this are obvious, being
severe discoloration of the paint
on the gear and cracks in any
exposed insulation. Similarly, a
bad contact at the lamp cap will
usually result in discoloration as
a sign of overheating.
Any fault finding must be done
by a competent electrician and,
if carried out with the luminaire
in place, under a permit to
work. With HPS and MBI, the
ignitor can become faulty. If the
lamp is fitted, the choke has
continuity and the connections
are good and correct they
should produce an "attempt to
start" effect in the lamp and a
buzzing sound from the ignitor.
It will be unusual to have no
other parts available to perform
a substitution fault finding
routine and this is the normal
procedure. Before re-
assembling, all connections
should be checked and any
damaged cable replaced. The
ignition connection to the
lampholder is sleeved with H.T.
sleeving and this must be kept
in place.
3.9.1 Thermal Protector
Thermal protectors are
included. If the lamp goes on
and off over a timescale of
several minutes, this could be
the thermal protector operating.
The causes are defective
lamps/diode effects, gross over
voltage or the choke beginning
to fail and this should be
investigated directly. See also
Section 3.4
.
4.0
Overhaul
The unit is largely made of
materials which are very
corrosion resistant. This allows
the unit to be completely
stripped, cleaned, then re-built
with new electrical parts as
required. The internal wiring is
1.0mm² flexible, silicone rubber
insulated. An H.T. sleeve is
fitted to the ignitor cable. All the
spares required are available.
Please state the model number,
lamp details.
The seal at the cover is
between the glass and the
frame. The glass is retained in
the cover frame by silicone
R.T.V. adhesive.
If the cover gasket has
deteriorated by softening or
permanent set, a new cover
gasket should be fitted. Which
can be obtained from Chalmit.
To fit this, care is needed, the
old gasket should be removed
and remaining adhesive
scraped off. The gasket is fixed
in place and joined with silicone
R.T.V. to the body. The cover
is tightened down and the
assembly should be tested for
air tightness prior to installation.
5.0
Fuse Ratings
The fuse ratings for HID lamp
circuits need to take account of
three components of circuit
current. Current inrush to PFC
capacitors which can be up to
25 x the rated capacitor current
and last 1-2 millisecs; lamp
starting current including steady
capacitor current which
together may decline from up to
200% of normal at 10 seconds
after switch-on to normal after 4
minutes; rectification effects
caused by asymmetrical
cathode heating for a few
seconds after starting, this
effect is random and very
variable. With the availability of
MCB's with a wide range of
characteristics, the individual
engineer can make a better
judgement of what is required.
Use MCB's suitable for inrush
currents to reduce ratings. The
inrush current can be calculated
where circuit conditions are
known. The nominal capacitor
current will probably be the
determining factor, 0.076A per
µF at 240V, 50Hz (adjust for
other supply volts by
multiplication, x 6/5 for 60Hz).
For HBC fuses use 1.5 x
normal capacitor current. All
calculations must satisfy wiring
regulations.
6.0
Disposal of Material
The unit is mostly made from
incombustible materials. The
capacitor is of the dry film type
and does not contain PCB's.
The control gear contains
plastic parts and polyester
resin. The ignitor contains
electronic components and
synthetic resins. All electrical
components and the body parts
may give off noxious fumes if
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