Azbil AUR450C - Solenoid Valve Wiring Safety

2-8
Chapter 2. MOUNTING AND WIRING
 Wiring to a solenoid valve
WARNING
Do not connect a solenoid valve to the high voltage side of the circuit. If a ground fault occurs,
the ground fault current may energize and open the solenoid valve. This device will not be able
to prevent the valve from opening and fuel from flowing out.
z Correct connection
High potential side (H)
(Ground fault)
Power supply
Burner
Combustion equipment
Valve (closed)
Low potential side (G)
Fuel
N L
AUR450C
When the valve wiring is connected correctly as shown in the figure above, current
does not flow through the solenoid valve even if a ground fault occurs due to faulty
insulation on the high voltage side (H). Therefore, the valve does not open and fuel
does not flow out.
z Incorrect connection
(Ground fault)
Burner
Valve (open)
Fuel
N L
High potential side (H)
Power supply
Combustion equipment
Low potential side (G)
AUR450C
If the valve wiring is connected to the high voltage side, current flows through the
solenoid valve if a ground fault occurs, as shown in the figure above. Therefore, the
valve opens in spite of the device and fuel flows out.