WNIP SEPT OCT 19.5 DIGITAL

10
Programmable time switch technology for temperature
control
This new generation of
programmable time switch
technology encompasses
AlphaRex³ and MicroRex time
switches for precise temperature
control in domestic, commercial
and industrial environments.
Rex time switches, with
analogue and digital dials, are
ideally suited for OEM’s and panel
builders who can pre-programme
the time switch during installation.
At a later stage when the panel or
product is connected to power,
all the end-user has to do is set the
real time. These programmable
time switches ensure high clock
precision, optimum reliability,
maximum safety and enhanced
aesthetics.
In temperature control
applications, these devices are
used to switch an electric circuit
on or off at selected times during
a pre-programmed time period.
These time switches also have an
automatic return facility and a
permanent forced switching on or
off override control.
Typical applications for time
switches in heating and cooling
installations include water heaters,
air conditioners, heating and
ventilation systems and swimming
pool heaters.
AlphaRex³ programmable
time switches have a userfriendly
standardised text guided
programming facility, with a high
resolution digital display and
backlight. There is a standard,
single data key for all devices in
this range to allow quick and easy
transfer of programmes to other
time switches and for creating back
up copies.
These time switches are
available with standard and
multiple functions, with a daily or
weekly programme facility and a
clock working reserve of six years.
Programming with clock
precision to the second is
controlled directly on the time
switch, or outside the distribution
board using a PC and Legrand’s
AlphaSoft programming software.
Other features include an EEPROM
memory which prevents settings
being lost and the facility to
programme the clock prior to
despatch. Once the unit has been
programmed, the information will
remain installed even if the switch
is not connected to power. The
battery can be removed without
having to uninstall the time switch
from the distribution board.
MicroRex time switches offer
easy plug and play installation for
daily and weekly programming.
By simply setting the analogue
switching dial during start up, the
time is automatically set using
the fast-run mode. In the event
of a power failure, the time is
automatically reset.
MicroRex analogue and
digital modules are 24 hour and
seven day time switches for DIN
rail and wall mounting, with a 100
hour running reserve. These units
have the capability for multiple
programmes, which ensures
optimum time setting flexibility.
MicroRex time switches have an
LED status indicator, a precision
clockwork of 0.2 s/day and are
controlled by either a quartz or
synchronous motor. For increased
safety and user convenience, there
is an automatic and manual and
advance/over-ride facility.
An analogue defrost switch
is available for short periods of
controlled defrosting. The timer
19.5
can repeat one or two settable
short programmes within 24 hours
and the defrosting time is from one
to 60 minutes per contact.
Other time switches in the
Legrand range are designed
for precise control in security
installations – for access points;
electric fences and alarms –
as well as for use in industrial
installations, including pump
stations, filters and conveyors.
Legrand time switches are also
used for the lighting of commercial
boards and signage, as well as for
street lighting. Time switches in
agricultural applications are used
for irrigation and sprinkler systems
and for cyclical programmes, like
animal feed systems.
legrand.south-africa@
legrand.co.za
VA purgemeters with surface passivation for trace-level
analysis
The option of surface
passivation for trace-level
analysis is now offered for the For
its variable area flow meters DK
32, DK 34 and DK 37.
Trace-level analysis is used for
providing evidence of very small
concentrations in the range of ppm
(parts per million) to ppb (parts per
billion).
Here, it is very important that
none of the particles to be detected
are already adsorbed in the sample
feed line as this would lead to a
delayed or even wrong analysis
result.
Examples are the
measurement of H2S content in
natural gas or oil, mercury, or NOx/
SOx flue gas analysis in various
industries.
To avoid adsorption, sample
feed lines, fittings and valves can be
surface passivated.
This can now also be applied
to the DK 32, DK 34 and DK 37 allmetal
purgemeters that are used
for adjustment and monitoring of
the sample flow to the analyser.
Before being assembled and
calibrated, all metal components
in contact with the medium such
as cone, float, valve components,
etc., receive a SilcoNert 2000 inert
silicon coating, a patented surface
treatment at a temperature of
400°C / 752°F.
The same is possible for wetted
metal components of DK 46, DK 47,
DK 48 and DK 800 glass devices.
salesza@krohne.com