Omron E2E-Y Datasheet page 10

Precautions for AC 2-wire Proximity Sensors in Operation
Connection
Model Connection type
AC 2-wire AND
(serial connection)
OR
(parallel connection)
10
Method
Incorrect
Load
Correct
Load
Load
Incorrect
Load
A
B
Correct
Load
A
B
If 100 or 200 VAC is imposed on the Proximity
Sensors, V (i.e., the voltage imposed on the load)
L
will be obtained from the following.
V = V – (residual voltage x No. of Proximity
L S
Sensors) (V)
Therefore, if V
L
voltage, the load will not operate.
A maximum of three Proximity Sensors can be
connected in series provided that the supply voltage
is 100 V minimum.
V s × 100 V
In principle, more than two Proximity Sensors
cannot be connected in parallel.
Provided that Proximity Sensor A does not operate
with Proximity Sensor B simultaneously and there is
no need to keep the load operating continuously,
the Proximity Sensors can be connected in parallel.
In this case, however, due to the total leakage
current of the Proximity Sensors, the load may not
reset properly.
VAC power
It is not possible to keep the load operating
supply V
S
continuously with Proximity Sensors A and B in
simultaneous operation to sense sensing objects
due to the following reason.
When Proximity Sensor A is ON, the voltage
imposed on Proximity Sensor A will drop to
approximately 10 V and the load current flows into
Proximity Sensor A, and when one of the sensing
objects is close to Proximity Sensor B, Proximity
Sensor B will not operate because the voltage
imposed on Proximity Sensor B is 10 V, which is too
low. When Proximity Sensor A is OFF, the voltage
imposed on Proximity Sensor B will reach the supply
voltage and Proximity Sensor B will be ON. Then,
Proximity Sensor A as well as Proximity Sensor B
will be OFF for approximately 10 ms, which resets
the load for an instant. To prevent the instantaneous
resetting of the load, use a relay as shown on the
left.
Cylindrical Inductive Sensor for AC Power Supply
Description
is lower than the load operating