BEKA BA377E, Руководство пользователя

Страница: 9 / 62

9
3.1.2 Sensor input
When configured as a Timer the sensor input may be
connected to a wide variety of hazardous area
devices as shown in Fig 1, or to safe area sensor as
shown in Fig 2. The input must be maintained not
momentary. The BA377E input is not used when the
instrument is configured as a Clock.
No Zener barrier is required in series with the input if
the intrinsically safe sensor is located within the
same hazardous area as the BA377E. The following
table shows the instrument's input switching
thresholds when configured to operate with various
sensors. For reliable operation the BA377E input
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 terminals 3 and 4 together as
described in section 2.5.
3.1.3 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, and the switch and associated wiring
can withstand a 500V rms insulation test to earth.
Most industrial push buttons and magnetically
activated reed relays comply with these
requirements. The BA377E contains a configurable
debounce circuit to prevent false triggering of the
instrument. Three levels of debounce protection are
available. See section 6.5.6.
3.1.4 Open collector input
Any sensor with an open collector output located in
the same hazardous area as the BA377E, 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
contains a configurable debounce circuit to prevent
false triggering. Three levels of debounce protection
are available. See section 6.4.6.
3.1.5 2-wire proximity detector input
Most intrinsically safe NAMUR 2-wire proximity
detectors may be connected to the BA377E sensor
input, providing the input safety parameters of the
proximity detector are equal to or greater than the
output safety parameters of a BA377E 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.
The BA377E contains a configurable debounce
circuit to prevent false triggering of the instrument.
Three levels of debounce protection are available.
See section 6.5.6.
3.1.6 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.