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

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OPERATION & SERVICE
Servicing should only be performed by a Qualified Service Agent
14
Checking Three Phase (3Ø) Power
A three phase power supply will be connected to the L1, L2 and L3 terminals of the Power
Distribution Block or directly to the contactor on models equipped with a single element. All three
wires are “hot” with voltage present. Check power supply voltage as follows:
1 With the power supply to the water heater turned on set the volt meter to an AC voltage range above the
expected voltage (600 VAC or higher range initially).
2 Measure and record the voltage at the water heater’s Power Distribution Block or at the contactor on single
element models. Measure voltage between; [L1 & L2], [L2 & L3] and [L1 & L3] terminals. This will be three
voltage readings at a Power Distribution Block or a 3 pole contactor. Models equipped with a single heating
element and a 4 pole contactor will require taking the voltage readings between the [L1 & L2] and [L2 & L3]
terminals twice since there are two L2 terminals on the contactor - total of 4 voltage readings. All voltage
readings should be approximately the same.
3 Measure and record the voltage between the L1 terminal and the ground wire connection to the water
heater. Check between L2 and ground and L3 and ground in the same way. Note: models equipped with a
single element and a 4 pole contactor will require four voltage readings; between the each of the 4 poles of
the contactor and ground. On some 208 volt power supplies each reading to ground will be approximately
120 volts. Some 208 volt models will have a “stinger leg” with one of the three readings to ground
measuring 208 volts - 208 volt stinger legs should be connected to L2. On 240 volt power supplies each
reading to ground should be approximately 120 volts. On 480 volt power supplies each reading to ground
should be approximately 277 volts.
Service Warning: Zero volt readings between terminals and ground can be due to an inadequate earth
ground. TREAT ALL WIRES AS BEING HOT until it has been determined there is no voltage present.
If the voltage readings between terminals (step 2) or the voltage between any of the terminals and
ground (step 3) was less than expected (< 95% expected): check power supply fuses, the breaker
and/or disconnect switch supplying power to the water heater. Contact a Qualified/Licensed
electrician to restore power. If the voltage readings taken in Step 2 above are a standard voltage
(208/240/480) but do not match the listed voltage on the water heater’s rating label secure power to
the water heater.
DO NOT place the water heater back in service. Call the toll free Technical Support
phone number listed on the back cover of this manual for further assistance.
208/240/480 Volt 3Ø Power
L1 L2 L3
Power Distribution Block
3 Pole Contactor
4 Pole Contactor
Measure power supply
voltage to water heater
on single element models
at upper terminals of the
contactor.
Measure power supply
voltage to water heater
on models with more
than one element at the
Power Distribution Block
Measure power supply
to heating elements on
all models at the lower
terminals of the
contactor(s).