SMC Networks VQC4000, Operation Manual

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No.VQC4000V-OMX0001
Design / Selection
1. Precautions on 2-position double
solenoid valve
If a double solenoid valve is operated with momentary
energization, it should be energized for at least 0.1
second. However, depending on the piping conditions,
cylinder may malfunction even when the double
solenoid valve is energized for 0.1 second or longer. In
this case, energize the double solenoid valve until the
cylinder is exhausted completely.
2. Leakage voltage
Take note that the leakage voltage will increase when a
resistor is used in parallel with switching element or a
C-R circuit (surge voltage suppressor) is used for
protecting a switching device because of the passing
leakage voltage through the C-R circuit.
The suppressor residual leakage voltage should be as
follows. Should be 3% or less of rated voltage.
3. Surge voltage suppressor
1) A surge voltage suppressor built into the valve is
intended to protect the output contacts so that the
surge generated inside valve does not adversely
affect the output contacts. Therefore, if an
overvoltage or overcurrent is received from an
external peripheral device, the surge voltage
protection element inside the valve is overloaded,
causing the element to break. In the worst case, the
electric circuit enters the short-circuit status by the
breakage. If the energizing continues in this status,
a large current flows. This may cause secondary
damage to the output circuit, external peripheral
device, or valve, and may also cause fire accident.
So, take appropriate protective measures, such as
installation of an overcurrent protection circuit in the
power supply or drive circuit to maintain the
sufficient safety.
2) If a surge protection circuit contains nonstandard
diodes, such as Zener diodes or varistor, a residual
voltage that is in proportion to the protective circuit
and the rated voltage will remain. Therefore, take
into consideration the surge voltage protection of
the controller.In the case of diodes, the residual
voltage is approximately 1 V.
4. Surge voltage intrusion
With non-polar type solenoid valves, at times of
sudden interruption of the loading power supply, such
as emergency shutdown, surge voltage intrusion may
be generated from loading equipment with a large
capacity (power consumption), and the solenoid
valve in a deenergized state may switch over (see
Figure 1).
When installing a breaker circuit for the loading
power supply, consider using a solenoid valve with
polarity (with polarity protection diode), or install a
surge absorption diode between the loading
equipment COM line and the output equipment COM
line (see Figure 2).
Caution
VQC4000 Series
Precautions for 5 Port Solenoid Valve 2
Be sure to read before handling. Refer to main text for detailed precautions on every series.