BEKA BA377E-SS, Manual

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3.2.2 Sensor inputs
As shown in Fig 5 the BA377E-SS input can be
directly connected to hazardous area sensor, or to
safe area sensors via isolators as shown in Fig 6.
Galvanic isolators are not required in series with the
input if the intrinsically safe sensor is located within
the same hazardous area as the BA377E-SS. The
input must be maintained not momentary.
The BA377E-SS may be used with a wide variety of
sensors, the following table shows the switching
thresholds for each type. For reliable operation the
input signal must fall below the lower threshold and
rise above the upper threshold.
Sensor
Switching thresholds
Lower Upper
Low voltage range 1.0V 3.0V
High voltage range 3.0V 10.0V
Proximity detector 1.2mA 2.1mA
Switch
100

1000

Open collector
2k

10k

Switch contacts, proximity detectors and open
collector sensors require energising which is
achieved by linking two BA377E-SS terminals
together as described in section 2.5.
3.2.3 Switch contact input
Any mechanically activated switch contact may be
directly connected to input terminals 5 & 6 providing
the switch is located in the same hazardous area as
the BA377E-SS, and the switch and associated
wiring can withstand a 500V rms insulation test to
earth. Most magnetically activated industrial push
buttons and reed relays comply with these
requirements. The BA377E-SS contains a
configurable debounce circuit to prevent false
triggering of the instrument. Three levels of
debounce protection are available.
See
section 6.5.6
3.2.4 Open collector input
Any open collector sensor located in the same
hazardous area as the BA377E-SS, such as a
mechanically activated opto-isolator, may be directly
connected to input terminals 5 & 6. The sensor and
the associated wiring must be able to withstand a
500V rms insulation test to earth.
The BA377E-SS contains a configurable debounce
circuit to prevent false triggering. Three levels of
debounce protection are available See section 6.5.6
3.2.5 2-wire proximity detector input
Most intrinsically safe NAMUR 2-wire proximity
detectors may be connected to the BA377E-SS
input, providing the input safety parameters of the
proximity detector are equal to or greater than the
output safety parameters of a BA377E-SS input. i.e.
Ui ≥ 10.5V dc
Ii ≥ 8.2mA dc
Pi ≥ 25mW
and the minimum operating voltage of the proximity
detector is less than 7.5V. The proximity detector
must be located in the same hazardous area as the
BA377E-SS.
The BA377E-SS contains a configurable debounce
circuit to prevent false triggering of the instrument.
Three levels of debounce protection are available.
See section 6.5.6
3.2.6 Magnetic pick-off input
CoiL
in the input configuration menu is a low level
voltage input intended for use with an intrinsically
safe magnetic pick-off sensor which is not suitable
for controlling the BA377E-SS,