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Wiring
6
Wiring
6.1
General wiring guidelines
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Electrical or electronic components which could cause interference (contactors, thyris-
tors, relay coils and solenoid valve coils) should be physically separate from data lines.
We recommend you use a sheet metal (MU metal) bulkhead between both areas.
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Data lines and power lines should be laid separately to avoid capacitive and inductive
interference (recommended minimum distance = 10 cm/3.94").
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Screened data lines should also be laid in a different cable duct to the main power
lines.
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Power lines should be as short as possible
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Power lines should be twisted pair cables.
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We recommend a max. length of 2 m for the USB cable, to guarantee reliable data
transfer.
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UL requirement: only use copper wiring that will withstand 60/75°C for the supply
voltage; maximum torque setting: 0.5-0.6 Nm.
6.1.1
Shielding
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Connect the power cable shield with low impedance to earth.
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Use only shielded data lines.
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For high-frequency reasons, we recommend that the shielding on the data line cable
(RS 232 cable) is earthed on both sides. If you are using longer cables and there is the
possibility of transient currents, we recommend one of the following methods:
–
–
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Connect data line shields to a bus bar.
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Make the connection of the bus bar to the control cabinet/system as short and with as
low impedance as possible.
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Fasten the braided shield to the shield bar over as large a surface area as possible
(e.g. with metal hose clips or PUK cable clips).
6.1.2
Measures to protect against interference voltages
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Wire-up inductive loads (e.g. contactor coils, relay coils and solenoid valve coils) using
suppression elements (e.g. RC networks). This is particularly important if these induct-
ive loads are very close to the power supply or are fed from the same supply.
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If strong magnetic fields are present, we recommend you use a bulkhead separator, i.e.
metal sheet (MU-metal).
Operating Manual PMI v507, PMI v512
1003981-EN-01
Use equipotential bonding conductors
Use electrical isolation
19
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