BEKA BA314E, Manual

Page: 34 / 58

Fig 13 Equivalent circuit of each alarm output
9.3.2 Intrinsic safety
Each alarm output is a separate galvanically isolated
intrinsically safe circuit with output safety parameters
complying with the requirements for
simple apparatus .
This allows the alarm output terminals A1 & A2 and A3
& A4 to be connected to almost any intrinsically safe
circuit protected by a Zener barrier or galvanic isolator
providing the output parameters of the circuit do not
exceed:
Uo 28V dc
Io 200mA
Po 0.84W
The maximum equivalent capacitance and inductance
between each set of alarm terminals is:
Ci = 22nF
Li = 4µH
To determine the maximum permissible cable
parameters Ci should be subtracted from the
maximum permitted external capacitance Co
specified by the certificate for the intrinsically safe
interface powering the alarm circuit, such as the
solenoid driver and switch transfer galvanic isolators
shown in Fig 14.
Fig 14 Typical alarm application
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