E2E/E2E2 E2E/E2E2
46
Environment
W
ater Resistivity
Do not use the Proximity Sensor underwater, outdoors, or in the
rain.
Operating
Environment
Be sure to use the Proximity Sensor within its operating ambient
temperature
range and do not use the Proximity Sensor outdoors so
that its reliability and life expectancy can
be maintained. Although
the
Proximity Sensor is water resistive, a cover to protect the Prox
-
imity Sensor from water or water soluble machining oil is recom-
mended
so
that its reliability and life expectancy can be maintained.
Do not use the Proximity Sensor in an environment with chemical
gas (e.g., strong alkaline or acid gasses including nitric, chromic,
and
concentrated sulfuric acid gases).
Connecting Load to AC/DC 2-wire Sensor
Refer
to the following before using AC or DC 2-wire Proximity Sen
-
sors.
Surge
Protection
Although the Proximity Sensor has a surge absorption circuit, if
there
is any machine that has a
large surge current (e.g., a motor or
welding machine) near the Proximity Sensor, connect a surge ab-
sorber
to the machine.
Leakage Current
When
the Proximity Sensor is OFF
, the Proximity Sensor has leak
-
age
current. Refer to pages
17 and
21 Leakage Current Character
-
istics.
In this case, the load is imposed with a small voltage and the
load may not be reset. Before using the Proximity Sensor, make
sure that this voltage is less than the load reset voltage. The AC
2-wire Proximity Sensor cannot be connected to any card-lift-off
relay (e.g., the G2A) because contact vibration of the relay will be
caused
by the leakage current and the
life of the relay will be short
-
ened.
Countermeasures
Against Leakage Current
AC 2-wire Models
Connect
a bleeder resistor as
the bypass for the leakage current so
that
the current flowing into the load
will be less than the load reset
current.
As shown in the following diagram, connect the bleeder
resistor
so
that
the current flowing into the Proximity Sensor will be 10 mA mini
-
mum
and the residual voltage imposed
on the load will be less than
the
load reset voltage.
Load
Bleeder resistor R VAC power
supply VS
Refer
to the following to calculate the bleeder resistance and the al
-
lowable
power of the bleeder resistor
.
R x
V
S
/(10 – I) (k
Ω)
P > V
S2/R (mW)
P: The
allowable power of the bleeder resistor
. (The actual power
capacity
of the bleeder resistor must be at least a
few times as
large
as the allowable power of the bleeder resistor
.)
I:
Load current (mA)
The following resistors are recommended.
100
V
AC (supply voltage): A resistor with a resistance of 10 k
Ω
max
-
imum
and an allowable power of 3 W minimum
200
V
AC (supply voltage): A resistor with a resistance of 20 k
Ω
max
-
imum
and an allowable power of 10 W minimum
If
these resistors generate excessive heat, use a resistor with a re
-
sistance of 10 kΩ maximum and an allowable power of 5 W mini-
mum
at 100 V
AC and a resistor with a resistance of 20 k
Ω
maximum
and
an allowable power of 10 W minimum at 200 V
AC instead.
DC 2-wire Models
Connect
a bleeder resistor as
the bypass for the leakage current so
that
the current flowing into the load
will be less than the load reset
current.
Load
Bleeder resistor R
Refer
to the following to calculate the bleeder resistance and the al
-
lowable
power of the bleeder resistor
.
R x
V
S/(iR
– i
OFF) (kΩ)
P > V
S2/R (mW)
P: The
allowable power of the bleeder resistor
. (The actual power
capacity
of the bleeder resistor must be at least a
few times as
large
as the allowable power of the bleeder resistor
.)
iR:
Leakage current of Sensors (mA)
iOFF:
Release current of load (mA)
The following resistors are recommended.
12
VDC (supply voltage):
A resistor with a resistance of 15 k
Ω
maxi
-
mum
and an allowable power of 450 mW minimum
24
VDC (supply voltage):
A resistor with a resistance of 30 k
Ω
maxi
-
mum
and an allowable power of 0.1 W minimum
Inrush Current
A load that has a large inrush current (e.g., a lamp or motor) will
damage
the Proximity Sensor
, in which case connect the load to the
Proximity
Sensor through a relay
.
Connection to a PLC
Required
Conditions
Connection
to a PLC is possible if the specifications of the PLC and
the Proximity Sensor satisfy the following conditions. (The mean-
ings
of the symbols are given below
.)
1. The
ON voltage of the PLC and the
the residual voltage of the
Proximity
Sensor must satisfy the following.
VON
x
V
CC
– V
R
2. The
OFF current of the PLC and the the leakage current of the
Proximity
Sensor must satisfy the following.
IOFF y Ileak
(If the OFF current is not listed in the specifications, take it to
be
1.3 mA.)
3. The
ON current of the PLC and the the control output (I
OUT
) of
the
Proximity Sensor must satisfy the following.
IOUT(min)
x
I
ON
x
I
OUT(max)
The
ON current of the PLC will vary
, however
, with the power
supply
voltage and the input impedance used as shown in the
following
equation.
ION
= V
CC
– V
R
– V
PC)/RIN