BEKA BA377E-SS, Manual

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3.2.7 Voltage input
Two voltage input ranges are independently
selectable in the BA377E-SS configuration menu,
VoLt5 L
and
VoLt5 H
. When configured for either of
the voltage ranges and terminals 3 and 4 are not
linked, the input terminals 5 and 6 comply with the
requirements for
simple apparatus . This allows the
inputs to be connected to any certified intrinsically
safe voltage source within the same hazardous area
as the BA377E-SS having output parameters equal
to or less than:
Uo ≤ 28V dc
Io ≤ 200mA dc
Po ≤ 0.84W
The BA377E-SS Timer may therefore be directly
connected to and controlled by most certified
intrinsically safe high level outputs.
The maximum permitted cable parameters will be
defined by the intrinsic safety certification of the
voltage source less the BA377E-SS input
parameters which are small and can often be
ignored.
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
3.2.8 Remote reset
Connecting the external reset terminals RS1 and
RS2 together will reset the BA377E-SS when
configured as a Timer and synchronise the displayed
time when configured as a Clock. Remote resetting
may be accomplished by any mechanically operated
switch located in the same hazardous area as the
instrument providing the switch and the associated
wiring can withstand a 500V rms insulation test to
earth. No galvanic isolator is required.
A BA377E-SS may also be remotely reset or
synchronised from the safe area. Any switch may
be used but a galvanic isolator or IS relay is required
to transfer the contact closure into the hazardous
area. Fig 5 illustrates how a BA377E-SS Timer may
be reset from both the safe and the hazardous area.
Note: The BA377E-SS can also be configured to
reset when the
&
and
*
push buttons are
operated simultaneously in the display mode for
more than two seconds - see 6.5.19
3.2.9 Control outputs - optional
Each of the two factory fitted optional control outputs
is a galvanically isolated single pole solid state
switch as shown in Fig 7. The outputs are polarised
and current will only flow in one direction. Terminals
A1 and A3 should be connected to the positive side
of the supply.
Ron = less than 5

+ 0.7V
Roff = greater than 1M

Note: Because of the series protection diode some
test meters may not detect a closed alarm
output
Fig 7 Equivalent circuit of each control output
Each control output is a separate galvanically
isolated intrinsically safe circuit with output safety
parameters complying with the requirements for
simple apparatus . This allows the control output
terminals A1 & A2 and A3 & A4 to be connected to
almost any certified intrinsically safe circuit protected
by a galvanic isolator providing the isolator has the
correct function and the output parameters do not
exceed:
Uo ≤ 28V
Io ≤ 200mA
Po ≤ 0.84W
The maximum equivalent capacitance and
inductance between each set of alarm terminals is:
Ci = 22nF
Li = 8µH (Effectively 0)
To determine the maximum permissible cable
parameters Ci and Li, plus those for any other
intrinsically safe instruments in the loop, should be
subtracted from the maximum permitted external
capacitance Co and inductance Lo specified by the
certificate for the galvanic isolator powering the
circuit as shown in Fig 8.