INSTALLATION
The
FireRight LT
kiln temperature controller may be installed on the kiln, or in a remote
enclosure. If installed on the kiln, the temperature at the mounting location must not exceed 130°F
during operation.
The control can be mounted in panels as follows:
1.
Provide a rectangular cutout measuring 4
1
/
8
”
wide by 5
1
/
8
” high.
2.
Insert the
FireRight LT
in this cutout and mark the locations for its four mounting
screws.
3.
Remove the control and drill
7
/
64
” pilot holes at the marked locations.
4.
Fasten the
FireRight LT
to the mounting panel using #6 self-tapping screws.
ELECTRICAL CONNECTIONS
All electrical connections are made at the tabs provided at the top and along the bottom edge of the
control’s circuit board, using ¼” push-on terminals.
The
FireRight LT
will work with 50/60Hz input power, either 110/120vac or 208/240vac. Small
kilns drawing less than 15 amps can be operated directly by the control’s output contact. Larger kilns
require a separate power relay, sized according to the nameplate current of the kiln.
The wiring diagram provided in this sheet illustrates a typical installation using a mechanical
contactor (power relay) on a 208/240vac kiln. If the particulars of your installation are somewhat
different:
1.
Connect the temperature sensor to the
S
+ (yellow wire) and
S-
(red wire) terminals.
Any
Type K thermocouple
may be used. The
FireRight LT
is unaffected by sensor
or extension wire resistance, although the sensor cable must by Type KX
thermocouple extension wire (do not use copper hookup wire.)
2.
For 120vac systems, connect terminal
L1
to
a
and terminal
b
to
L4
.
3.
For 220vac systems, connect terminal
a
to terminal
b
.
4.
Connect one leg of the input power to terminal
L1
, and the other to
L4
. (Most
power relays have auxiliary terminals that are intended as a convenient source of
control power.
L1
and
L4
can usually be connected to the power relay at these
auxiliary terminals.)
5.
Connect the output contact of the
FireRight LT
to interrupt current either to the
kiln’s electric heaters, or the solenoid coil of the power relay. This normally open
contact is provided between terminals
H1
and
H2
.
6.
If operating the kiln’s electric heaters directly, connect one leg of the power line to
H1
, one end of the heating element to
H2
. Connect the other end of the heating
element to the other leg of the power line.
7.
If using a power relay, connect
H2
to
L1
, then connect
H1
to either one of the
power relay’s coil terminals. Next connect the second coil terminal to a
L4
auxiliary
terminal on the same power relay.
Please note that the
FireRight LT
modulates power to the kiln on an
ON/OFF
basis. Kilns are often
equipped with a motor-driven shut-off timers; in such cases, the power relay should be connected so
that it does not interrupt power to the timer. Please also note that certain types of mercury relays,
when used to switch high electrical heater current, can be highly inductive, and may cause the
FireRight LT
output contact to switch erratically. If any “chattering” is evident (
HEAT
light
flickering), consider attaching a
snubber network
(available from any electrical supply) across the
relay’s solenoid coil.
b
a
L1
H1
L4
H2
PO
WE
R C
OR
D
FR
OM
TO
H
EA
TE
RS
S+
S-
Typical System Wiring – 208/240vac 50/60 Hz Connections