Chapter 5 Electrical System; Overview; Primary Circuit - Cleveland SteamCraft V Service Manual

OVERVIEW

PRIMARY CIRCUIT

CHAPTER 5. ELECTRICAL SYSTEM
The SteamCraft V electrical system has three separate power circuits
shown in the block diagram, Figure 5-1. They are the primary (high
voltage) circuit, the 120 VAC circuit, and the low voltage control circuits.
Normally open relay contacts provide the interface among the three
circuits.
Wiring diagrams and schematic diagrams are located in Chapter 6. Table
6-1 lists serial numbers and their applicable wiring and schematic
diagrams. The schematic and wiring diagrams are at the end of Chapter
6. Refer to Table 6-1 to find the wiring and schematic diagrams that apply
to the unit being serviced.
The primary circuit taps high voltage (208, 230, or 460 VAC) directly from
the external power source connected to the terminal block. A three-pole
terminal block is used for delta connections; a four-pole terminal block is
used for wye connections. This circuit powers the primary coil of the
transformer, the steam generator heater elements, the fan motor, and the
fan heater element.
The 120 VAC circuit draws its power from the 120 VAC secondary
windings of the transformer. This circuit supplies power to contactors and
solenoids which control high voltage and water flow. The front and rear
contactors control power to the heaters and fan motor. The solenoids
control the water fin and condenser spray valves.
The low voltage circuit draws power from the 18 VAC secondary windings
of the transformer. The 12-VDC power supply is on the control board. It
provides regulated DC power to the temperature sensors, to the relays
that control the 120 VAC contactors and solenoids, and to the timing,
display and safety circuits. A high frequency section (15-20 kHz) supplies
power to the water level probes.
The following must be isolated from around: all high voltage
(208-480 VAC) input, heater, transformer primary wiring,
transformer secondary circuits (18 and 120 VAC),
secondary loads, and switching devices (including relay
circuits on control boards).
The primary circuit draws power directly from the external power lines.
For proper SteamCraft V operation, the electrical characteristics of the
primary circuit components must match the external supply voltage, cont.
CET-16 Service Manual
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