A.O. Smith DSE-5, Руководство по обслуживанию

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Servicing should only be performed by a Qualified Service Agent
39
OPERATION & SERVICE
TRANSFORMERS
This section of the manual provides information on how to check wiring and test the multiple
tap 120 VAC Control Circuit Transformer and the 24 VAC transformer - see Figures 1 and 2
on pages 8 & 9 for location of the transformers.
Service Note: There are two different 120 VAC transformers used on the water heaters
covered in this manual. One is used on water heaters factory configured for 208/240/277
volts. The other is used on 380/480 volt models. Both are multi tap transformers and primary
winding wiring configuration is similar.
120 VAC Transformer Wiring - 208/240/277 Volt Models
This is a multiple or “multi” tap transformer that can accept 3 different input voltages to it’s
primary winding. This transformer outputs 120 VAC power from it’s secondary winding which
powers the CCB (page 50) and the contactor coils. The input power wiring to the primary
winding of this transformer must be configured to match the power supply voltage to the
water heater. Incorrect wiring can cause output voltage from the transformer’s secondary
winding to be too low or too high. This can cause “contactor chatter” (contacts open and
close rapidly) and may permanently damage the contactors and/or the CCB. The
instructions below show how to properly configure the input power wiring to the transformers
primary winding.
1 Determine power supply voltage to the water heater - see pages 12 - 14. Ensure the power supply wiring to
the 120 VAC transformer’s primary winding are connected to the proper terminals as shown in the table
below.
2 Only one wire needs to be moved on the transformer’s primary winding terminals to configure for a
different voltage. Do not move or change the wire connected to the H1 terminal on the primary winding. Do
not move or change either wire at the secondary winding X1 or X2 connections.
WATER HEATER POWER SUPPLY VOLTAGE PRIMARY WINDING CONNECTIONS
208 VAC H1 Common & H2 (208)
240 VAC H1 Common & H3 (240)
277 VAC H1 Common & H4 (277)
H1 H2 H3 H4
Primary Winding
Secondary Winding
X1 X2
120 VAC