Amperage Table/Overcurrent Protection; Heater Circuits - Electronic Control Models; Control Circuit - Electronic Control Models - State Water Heaters 100 Series Instruction Manual

aMperaGe taBle/oVercurrent protectIon

The rating of the overcurrent protection must be computed on the
basis of 125% of the total connected load amperage. Where the
standard ratings and settings do not correspond with this computation,
the next higher standard rating or setting should be selected.

heater cIrcuIts - electronIc control Models

The water heater's electrical components are pictured and identified
in Diagrams 1 and 2. The model and rating plate illustration on page
6 identifies heater circuit ratings. The ELECTRONIC CONTROL
model has two electrical circuits.
• The control circuit, which controls the electrical power to heating
elements, referring the following control circuit diagram Figure 6.
• The power circuit, which is operated by the control circuit carries the
electrical load of the heating elements. The following describes the
heater circuits and includes wiring diagrams for Delta configuration,
refer to the "WYE Configuration diagrams" for water heaters operating
at 380V/400V/415V/575V. All heater circuits are designed for 50/60
cycle alternating current.

control cIrcuIt - electronIc control Models

These models are equipped with an electronic control system. The
system includes a CCB (Central Control Board) circuit board, an
immersion temperature probe with ECO for temperature sensing
and limiting, a UIM (User Interface Module) for user interface &
information display and element current sensors for monitoring the
power circuits. Refer to the control circuit label on the water heater
for details. The CCB is powered by a small 120V/24V transformer.
The control circuit operates on 120V supplied by a larger 100VA
FIgure 6. - 120 vAc coNtrol cIrcuIt trANSForMer coNNectIoNS - electroNIc coNtrol MoDelS
transformer. Standard equipment includes control circuit fusing using
two, 3 amp, class G fuses with 600 volt rating. Do not substitute
fuses of a different rating.
Sequence of Operation
1. When the control is powered, the UIM should display model
information, water temperature, Operating Set Point, heating
status and operating mode.
2. If the control determines that the actual water temperature inside
the tank is below the programmed Operating Setpoint minus the
(1st) differential, a call for heat is activated.
3. After all safety checks are verified, the CCB will energize
contactor coils starting with the lower bank of heating elements
(each diagonal row of three heating elements is considered a
"bank" - see Diagram 1) then energize the middle bank (if so
equipped) and top bank (if so equipped). The middle and top
banks (if so equipped) are energized according to programmed
2nd and 3rd differential set points.
4. The control remains in the heating mode until the water temperature
reaches the programmed Operating Setpoint. At this point the
contactors will be de-energized in the reverse order.
5. The control system now enters the standby operating mode
while continuing to monitor the water temperature and the state
of other system devices. If the water temperature drops below
the programmed Operating Setpoint minus the (1st) differential,
the control will automatically return to step 2 and repeat the
heating cycle.
NOTE: See the Electronic Control Models Operation section for
more detailed information on temperature settings mentioned above.
22