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

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Servicing should only be performed by a Qualified Service Agent
41
OPERATION & SERVICE
120 VAC Control Circuit Transformer Test
1 Ensure the main breaker or disconnect switch is turned on.
2 Verify with an AC volt meter that proper voltage is present at the Power Distribution Block or the contactor
on single element models (see Figures 1 and 2 on pages 8 & 9 and pages 12 - 14).
3 Check Primary Winding Voltage: Using an AC volt meter; set the volt meter to an AC voltage range
above the expected voltage (600 VAC or higher range initially). Touch the two volt meter probes between
the control circuit transformer’s primary winding H1 common terminal and the other primary winding
terminal with a power wired connected to it as shown in the “Primary Winding Voltage Test” image below -
see pages 39 & 40. Voltage between these two terminals should match the water heater’s power supply
voltage. If the voltage at the primary winding terminals of the transformer matches the water heater’s
power supply voltage the primary winding is being powered correctly. If the voltage measured is zero volts
or considerably less or more than the water heater’s power supply voltage:
• Check the control circuit fuses - see the Fuse test procedure on page 15.
• Check the wiring between the 120 VAC Control Circuit Transformer’s primary winding and the
Control Circuit Fuses see Figures 1 and 2 on pages 8 & 9 for location - ensure wiring is correct and
connections are tight and making good contact.
• Check the wiring between the Control Circuit Fuses and the Power Distribution Block or contactor
on single element models - ensure wiring is correct and connections are tight and making good
contact.
• Verify 120 VAC Control Circuit Transformer wiring is correct - see pages 39 & 40.
4 Check Secondary Winding Voltage: Using an AC volt meter; set the volt meter to an AC voltage range
just above 120 VAC. Touch the two volt meter probes between the Control Circuit Transformer’s secondary
winding X1 and X2 terminals as shown in the “Secondary Winding Voltage Test” image below. There
should be approximately 120 VAC present between these two terminals. If the voltage measured is
approximately 120 VAC the Control Circuit Transformer is operating properly. If the voltage measured is
zero volts or considerably less or more (± 10%) than 120 VAC AND all Steps above have been completed
and the results were successful - replace the Control Circuit Transformer. When replacing the Control
Circuit Transformer check all wiring to and from the transformer for pinched or shorted wires - repair or
replace damaged wiring as necessary.
Service Note: A continuity test can also be performed on the Control Circuit Transformer primary and
secondary windings to determine if either winding is an open circuit. Secure power to the water heater.
Disconnect all wiring to the transformer. Using an ohm meter check for continuity between the terminals on
the primary and secondary windings checked in Steps 3 and 4 above.
Primary Winding Voltage Test Secondary Winding Voltage Test