Burkert Type 8035 - Manual (Page 21)

21
Wiring
Type 8025/8035 /
• Use a filtered and regulated 12-36 V DC power supply.
The circuit has to be safety extra low voltage (SELV), with
a safe energy level
• Make sure the installation is equipotential. See chap. "8.1".
• Use shielded cables with an operating temperature limit
of 80 °C minimum.
• Do not install the cables near high voltage or high
frequency cables; If a combined installation cannot be
avoided, a minimum space of 30 cm should be respected.
• Protect the power supply by means of a 300 mA fuse and
a switch.
• Protect the relays by means of a max. 3 A fuse and a
circuit breaker (depending on the process).
• Do not apply both a dangerous voltage and a safety extra-
low voltage to the relays.
8.1. making the installation
equipotential
To ensure the equipotentiality of the installation (power supply -
device - fluid):
→
Connect together the various earth spots in the installation to
eliminate the potential differences that may occur between dif-
ferent earthes.
→
Observe faultless earthing of the shield of the power supply
cable, at both ends.
→
Connect the negative power supply terminal to the earth to sup-
press the effects of common mode currents. If this connection
cannot be made directly, a 100 nF/50 V capacitor can be fitted
between the negative power supply terminal and the earth.
→
Special attention has to be paid if the device is installed on
plastic pipes because there is no direct earthing possible.
Proper earthing is performed by earthing together the metallic
instruments such as pumps or valves, that are as close as pos-
sible to the device. If no such instrument is near the device,
insert metallic earth rings inside the plastic pipes upstream and
downstream the device and connect these parts to the same
earth. The earth rings must be in contact with the fluid.
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