Stahl 9411/24 Series, Руководство по эксплуатации

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Function and Device Design
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207321 / 941160310190
2018-04-16·BA00·III·en·04
Zone 2 Ex i Field Device Coupler 8 Spurs
Series 9411/24
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Mode of operation
Each field device can be supplied with a maximum current of 40 mA.
In total, max. 160 mA are available for rated operation. This current can be divided
between the field devices connected e.g.:
• 4 x 40 mA
• 8 x 20 mA
• 1 x 40 mA + 7 x 16 mA
• 1 x 30 mA + 7 x 18 mA
• 6 x 23 mA
• 5 x 28 mA
• 4 x 15 mA + 4 x 25 mA (only if option "Short circuit check" is deactivated)
A tester can also be connected to a spur until a total current of 40 mA is reached.
In order to do this, the "Short circuit check" option in the "Fieldbus Wizard" of the
calculation tool must be activated when verifying the segment. This permits any number
of short circuits on a field device coupler under normal load. Within the segment,
short circuits are permitted on the spurs of a field device coupler.
As short-circuit protection, each spur is equipped with a current limiting function to 50 mA.
An EOL resistor is installed. This can be activated or deactivated with a jumper.
Cable shields can either be capacitively or directly earthed. Trunks and spurs can be
earthed differently (see the chapter "Earthing and shielding").
The trunk voltage supplied to the field device coupler is monitored to ensure that no
undervoltage occurs. Its status is indicated by an LED. Other LEDs indicate the status of
the spurs, see chapter "Indications".
The field device coupler is equipped with power management to minimise the current
load of the trunk.
Power management
Soft start:
The soft start function activates the spurs one after the other. Staggering the activation
prevents a large amount of start-up current flowing through the field devices. This means
that the fieldbus power supply used is protected from current spikes and operation of the
field device coupler is not impaired by the voltage drop.
Short-circuit switch-off:
In the event of a short circuit, the affected spur is deactivated until the short circuit is
eliminated. In the event of a short circuit in several spurs, no more than one short-circuit
current is loaded into the trunk. This minimises the current consumption of the trunk and
the power dissipation of the field device coupler in all operating conditions.