Det-Tronics U7602B-P Unitized UV Flame Detector/Controller - Manual (Page 11)

WIRING REQUIREMENTS
The system should be wired using a 16 to 22 gauge
(1.5 to 0.5 mm
2
) cable. If the current signal output
line is used, it must be a separate shielded wire to
protect against interference. In applications where
the wiring cable is installed in conduit, the conduit
should not be used for wiring to other electrical equip-
ment.
NOTE
It is important to use cable that is suitable for the
installation environment. In applications involv-
ing high humidity or saltwater, use a cable that is
made specifically for harsh, saltwater environ-
ments. In all cases, typical cable insulation resis-
tance should be at least 100 megohms. If the
resistance drops below 10 megohms, the cable
could be deteriorating and should be replaced to
avoid shorting out the system. When testing the
insulation resistance, disconnect the leads from
the detector/controller before connecting the
megohmmeter (insulation tester) to the cable.
Since moisture can be detrimental to electronic
devices, it is important that moisture not be allowed to
come in contact with the electrical connections of the
system. Moisture in the air can become trapped with-
in sections of conduit, therefore the use of conduit
seals is required to prevent damage to electrical con-
nections caused by condensation within the conduit.
These seals must be watertight and explosion-proof
and are to be installed even if they are not required
by local wiring codes. A seal must be located more
than 18 inches (46 cm) from the unit. When an explo-
sion-proof installation is required, an additional seal
must also be installed at any point where the conduit
enters a non-hazardous area.
When pouring a seal, the use of a fiberdam is
required to assure proper seal formation. The seals
should never be poured in temperatures that are
below freezing, since the water in the sealing com-
pound will freeze and the compound will not dry prop-
erly. Contamination problems can then result when
temperatures rise above the freezing point and the
compound thaws. The shielding of the cable should
be stripped back to permit the seal to form around the
individual leads, rather than around the outside of the
shield. This will prevent any siphoning action that
might occur through the inside of the shield.
Moisture in the air can be trapped within sections of
conduit and can condense and accumulate at the
base of vertical conduit runs. To eliminate this condi-
tion, explosion-proof drains and breathers should be
installed to automatically bleed off accumulated water.
When using steel wire armored or mineral-insulated
copper-sheathed cables, select an approved gland
with a watertight compression stage and an overall
gland shroud for outdoor applications. A sealing
washer must be fitted between the gland and the con-
duit entry to ensure IP66 rating.
WIRING AND MOUNTING PROCEDURE
After determining the correct positioning and density
of the U7602(s), use the procedure below for mount-
ing and wiring the unit(s). For reference, Figure 10
shows TB1 power and oi test connections, Figure 11
shows the TB3 configuration for standard relay and
current outputs and Figure 12 shows the optional
Form C relay and 4 to 20 ma current outputs. Figures
13 and 14 show typical U7602 wiring diagrams for
systems that use end of line resistors. See Figure 15
for systems that use end of line capacitors.
NOTE
When the U7602 is used with external monitoring
equipment, the equipment that monitors the Fault
relay contacts should have a 5 second time
delay during power-up to avoid nuisance fault
annunciation.
8
U7602 DETECTOR/CONTROLLER
CURRENT OUTPUT
FAULT RELAY CONTACTS
(NORMALLY CLOSED)
TB3
1 2 3 4 5
FIRE RELAY CONTACTS
(NORMALLY OPEN)
}
}
A1492
Figure 11—TB3, Relay and Current Outputs
for Standard Controller Module
Figure 10—TBI, Power and oi Test Connections
NC NO C
ALARM A1664
NC NO C
FAULT*
MA
4 TO 20
* FAULT RELAY IS NORMALLY
ENERGIZED WITH POWER APPLIED
AND NO FAULTS PRESENT.
FAULT RELAY SHOWN DE-ENERGIZED
Figure 12—TB3, Relay and Current Outputs
for Optional Form C and 4 to 20 ma Controller Modules