Carbolite GHA Installation, Operation & Maintenance Instructions Manual page 16

G range
3-phase without neutral (delta)
In most instances this diagram does not apply. See 7.7. It may apply if non-standard models are
ordered.
Filter (if fitted)
L3
L2
F1
L1
F2
PE
7.5 Higher Voltages
For 254V or above 1-phase or 440/254V or above 3-phase an isolating transformer is fitted in the
control circuit after the F2 fuses.
This addition may be applied to diagrams 7.1, or 7.3.
7.6 Three-Zone models
The element circuit in the 3-zone versions remains the same as in diagrams 7.3, 7.4 or 7.7, but the
control circuit contains three controllers and additional thermocouples. The sub-circuits for the
three control methods referred to in section 3.2 are:
slave
controller +
–
master
controller +
–
slave
controller +
–
thermocouples
Control type A
Control type B - the diagram is like C, plus the connections between the controllers indicated in
section 3.2 C.
16
Instrument Switch
heater
switch
if fitted
overtemp.
controller
thermocouple
temperature
controller
thermocouple
SSR
slave
SSR
main
+
ref.
–
SSR
slave
contactor
coil
SSR
SSR
SSR
slave
controller
master
controller
slave
controller
Control type C
F3 F3
e e
l l
e e
m m
heat
heat
e e
on
on
n n
t t
(s) (s)
F3
F3
F2
transformer
F2
Instrument Switch
SSR
end
SSR
centre
SSR
end
thermocouples
MF48 -1.18
F3
e
l
e
m
heat
e
on
n
t
(s)
F3