65
Rev. 2
POLARIZATION AND PHASING
As more and more electronic's are introduced to the Heat-
ing Trade, Polarization of incoming power and phasing of
primary to secondary voltage on transformers becomes more
important.
Polarization has been apparent in the Appliance industry
since the introduction of the three prong plug, however, the
Heating Industry does not use a plug for incoming power,
but is hard wired.
Some of the electronic boards being used today, with flame
rectification, will not function properly and/or at all without
polarization of incoming power. Some also require phasing
between the primary and secondary sides of step-down trans-
formers.
To instill new working habits for our trade, we recommend
that these two items be checked during normal installation
and/or service calls. See as follows:
This is L1 or the
Hot power leg
Incoming Power
This is the Common
or Neutral Leg
Meter Reads
120 Volts
Meter Reads
0 Volts
GN
D
GN
D
Volt / Ohm
Meter
Volt / Ohm
Meter
These then should be wired to the furnace accordingly.
If meter reads approximately 96 volts - the primary to secondary are in phase - if reads approximately 144 volts out of phase
- reverse low voltage wires.
*Note: For flame rectification the common side of the secondary voltage (24 V) is cabinet grounded. If you were to bench
test a transformer the primary neutral and secondary common must be connected together for testing purposes.
CHECKING FOR PHASING - PRIMARY TO SECONDARY OF UNMARKED TRANSFORMERS*
C
R
GN
D
Neutral
L1
Phasing Symbol
24 V
120 V
Some transformers will display phasing symbols as shown
in the illustration to the left to assist in determining proper
transformer phasing.
Checking for polarization and phasing should become a habit
in servicing. Let's start now.
Note: The new Heatcraft HSI-2 integrated ignition control
used on the GUID model furnace, has a diagnostic flash
code for reversed polarity. The diagnostic light code for this
problem is six short flashes followed by a pause. (Refer to
TROUBLESHOOTING-DIAGNOSTIC CHART on pages 50
and 51).
.
. .
.
. .
VO L T / O H M
M E TE R
GN
D
Pr
im
a
ry
Se
c
o
n
d
a
ry
Transformer
R
C
Meter Reads
24 Volts
Line Voltage
(Neutral)
Line Voltage
L1 (Hot)
VO L T / O H M
M E TE R
Meter Reads
120 Volts
VO L T / O H M
M E TE R
C
R
GN
D
N
L1
VO L T / O H M
M E TE R
Reads 96 Volts - In Phase
C
R
GN
D
N
L1
VO L T / O H M
M E TE R
Reads 144 Volts - Out of Phase
Содержание GCIA045A30
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