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Flame supervision
Flame supervision with
ionization probe
Ionization current
supervision with AC 110
V burner controls
Connection of
transformer
Building Technologies Division
Detector voltage between terminals 1 and
2 or ground
(AC voltmeter Ri 10 M)
Recommended detector current to ensure reliable
operation
Possible detector current in operation
Length of detector cable
Required insulation resistance between
ionization probe with its cable and ground
The conductivity and rectifying effect of hot flame gases are used for flame supervision.
For that purpose, AC voltage is applied to the heat-resistant ionization probe which
projects into the flame. The current that flows in the presence of a flame (ionization
current) generates the flame signal which is fed to the input of the flame signal
amplifier. The amplifier is designed so that it only responds to the DC current
component of the flame signal, thereby ensuring that a short-circuit between ionization
probe and ground cannot simulate a flame signal (since AC current would flow in this
case).
Since the ionization current with AC 110 V burner controls is only around half of those
operating on AC 230 V, the detector voltage must be increased with a transformer in
certain cases.
Capacity of transformer: Min. 2 VA
Transforming ratio: Approx. 1.1...1.5
The primary and secondary windings must be galvanically separated.
AC 115 V
L
N
12
2
1
LGB2...
At mains voltage UN = AC 230 V
Max. 20 m (separate cable)
Min. 50 M
ION
AC 127...172 V
U
N
Min. 5 µA
Max. 100 µA
9/15
CC1N7418en
21.06.2016
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