Azbil AUR890 Series - Page 28

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Chapter 2. Installation, Wiring
z Connections to solenoid valve
WARNING
Do not connect the solenoid valve to the high potential side (L1). If it is connected to L1 and a
ground fault occurs, current can leak to the solenoid valve and open it, allowing fuel to flow out,
regardless of the status of the burner controller.
 Correct method of connection
If the solenoid valve is properly connected as shown above, current will not leak
to the solenoid valve and an uncontrolled fuel flow will not occur if there is a
ground fault due to insulation failure on the high potential side (H).
 Wrong method of connection
If the solenoid valve is connected to the high potential side (H) as shown in the
figure above, and a ground fault occurs, current can leak to the solenoid valve
and open it, causing an uncontrolled flow of fuel regardless of the status of the
burner controller.
High-voltage side (L1)
Low-voltage side (L2(N))
(Ground-fault)
Power supply
Burner Controller
Burner
Combustion
equipment
Valve (close)
Fuel
N L
High-voltage side (L1)
Low-voltage side (L2(N))
(Ground-fault)
Valve (open)
Fuel
N L
Power supply
Burner Controller
Burner
Combustion
equipment