22
MAN0604_Issue 09_02-2013
Apex
2110M8030
6.
Any electrical interference induced onto the 4-20mA loop conductors by the installation must
be kept below the levels necessary to comply with the general requirements of EN50270.
In practice, this means that peak noise currents induced on the current loop should be no
greater than ± 0.25mA.
7.
The 0V rail of the control card/system is often directly connected to one side of the 4-20mA
current sensing resistor. Electrical noise on such a rail is therefore directly connected to the
4-20mA input. In order to avoid additional noise being induced on the 0V rail, it should not be
common with the safety earth/ground which frequently carries a high level of electrical noise.
8.
The 24V supply should be free from large transients and fluctuations.
The type of cable used for field wiring between the Apex transmitter and control equipment, and
between the Apex transmitter and Apex sensor if mounted remotely, should be selected to meet the
environmental and hazardous area requirements. The cable internal construction should be a of the
screened, multi-core, multi-stranded type. The terminals within the product will accept a maximum
conductor size of 2.5mm
2
(14AWG). The recommended minimum conductor size is 0.75mm
2
(20AWG). The conductors should be sized to give a total power supply loop resistance of less than
30 Ohms (ECC cartridge) or 16 0hms (Catalytic cartridge).
If remote mounting the sensor from the transmitter a 4-core, screened cable with a minimum
conductor size of 0.75mm
2
(20AWG) is required.
3.1 TRAnSmiTTER UniT And cERTiFiEd SEnSOR
This installation consists of a Transmitter Unit with Certified Sensor locally mounted at the
Transmitter Unit together with field wiring.
To/from
controller
Apex Transmitter Unit
with Certified Sensor
Apex Transmitter Unit
with Certified Sensor
(North America-style
installation)
Apex Transmitter Unit
with Certified Sensor
(European-style
installation)
The system components can be installed by a single technician.
This procedure describes how to:
•
install a Transmitter Unit
•
fit a Certified Sensor to the local Transmitter Unit
•
connect up the Certified Sensor and field wiring
•
configure the Transmitter Unit relay and alarm settings
•
install a gas sensing cartridge into the Certified Sensor
Refer to the
General Installation Guidelines
at the beginning of this chapter.
3. inSTAllATiOn
Apex Transmitter Unit
with Certified Sensor mounted
in Certified Junction Box
(European
-style installation)
Certified Junction Box
with Certified Sensor
Apex Transmitter Unit
o