SMC Networks SV Series Manual page 3

3/4/5-Port Solenoid Valves
Precautions 3
Be sure to read this before handling products.
Caution
2) The valve does not turn OFF.
If the PWM circuit built-in type valve is driven by the photo
coupler, the photo coupler cannot turn OFF and the valve is
kept in an ON state. Therefore, take great care when using
the photo coupler built-in SSR (solid state relay) or drive
circuit.
Applicable solenoid valve series with power-saving circuit
• SY (High pressure type), VF, VP, V100 (Large flow type:
Type U)
• VQ100, VQD1000, S070
4. Solenoid valve drive for AC with a solid state
output (SSR, TRIAC output, etc.)
1) Current leakage
When using a snubber circuit (C-R element) for surge
protection of the output, a very small amount of electrical
current will continue to flow even during the OFF state.
This results in the valve not returning. In a situation where
the tolerance is exceeded, as in the above case, take
measures to install a bleeder resistor.
2) Minimum allowable load amount (Min. load current)
When the consumption current of a valve is less than the
output's minimum allowable load volume or the margin is small,
the output may not switch normally. Please contact SMC.
3) Solenoid valve with full wave rectifier circuit
When the solenoid valve built-in full wave rectifier circuit
with AC specifications is used, a return failure of the
solenoid valve may occur depending on the kind of triac
output circuit. Carefully check this point when selecting a
SSR or sequencer.
For details, contact the SSR or sequencer manufacturer.
5. Surge voltage suppressor
1) The 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 breakage causes the electric circuit to enter
short-circuit status. If energizing continues while in this state, a
large current flows. This may cause secondary damage to the
output circuit, external peripheral device, or valve, and may
also cause a fire. So, take appropriate protective measures,
such as the installation of an overcurrent protection circuit in
the power supply or a drive circuit to maintain a sufficient level
of 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.
5
A
Design/Selection
6. Surge voltage intrusion
Applicable series (non-polar type solenoid valves)
VQ100 and 3/4/5-port solenoid valves VQ(C), VQZ, VQD (2
W type) series
SY100, V100, and 3/4/5-port solenoid valves SY, SYJ, SX,
SZ, SV, SJ, VF, VP series
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 a solenoid valve in a de-energized 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).
Output circuit
Figure 1. Surge intrusion circuit example (NPN outlet example)
Output circuit
Figure 2. Surge intrusion countermeasure example (NPN outlet example)
sol. 1: Holding
R
sol. 2:
Non-holding
R
Large capacity
load: Holding
R
Relay
Power supply circuit breaker
24 VDC
sol. 1: Holding
R
sol. 2:
Non-holding
R
Large capacity
R load: Holding
Diode
– (Anode) + (Cathode)
Relay
Power supply circuit breaker
24 VDC
Surge voltage
24 V
0 V
−60 V
Surge voltage
24 V
0 V
−60 V
Surge voltage
24 V
0 V
−60 V
Surge voltage
24 V
0 V
−2 V
Surge voltage
24 V
0 V
−2 V
Surge voltage
24 V
0 V
−2 V
Countermeasure parts