Vega VEGABAR 52 4 … 20 mA Bedienungsanleitung PDF herunterladen (Seite 15)

5 Connecting to power supply

VEGABAR 52 • 4 … 20 mA

36716-EN-130321

5 Connecting to power supply

5.1 Preparing the connection

Always keep in mind the following safety instructions:

•

Connect only in the complete absence of line voltage

•

If overvoltage surges are expected, overvoltage arresters should

be installed

Tip:

We recommend using VEGA overvoltage arresters B63-48 and

ÜSB 62-36G.X.

Inhazardousareasyoumusttakenoteoftherespectiveregulations,

conformityandtypeapprovalcerticatesofthesensorsandpower

supply units.

Power supply and current signal are carried on the same two-wire

cable.Thevoltagesupplyrangecandierdependingontheinstru-

ment version.

Thedataforpowersupplyarespeciedinchapter"Technical data".

Provide a reliable separation between the supply circuit and the

mains circuits according to DIN EN 61140 VDE 0140-1. The VEGA

power supply units VEGATRENN 149A Ex, VEGASTAB 690 as well

as all VEGAMETs and VEGASCANs meet this requirement.

Keepinmindthefollowingadditionalfactorsthatinuencetheoperat-

ing voltage:

•

Output voltage of the power supply unit can be lower under nomi-

nal load (with a sensor current of 20.5 mA or 22 mA in case of fault

message)

•

Inuenceofadditionalinstrumentsinthecircuit(seeloadvaluesin

chapter"Technical data")

The instrument is connected with standard two-wire cable without

screen. If electromagnetic interference is expected which is above the

test values of EN 61326 for industrial areas, screened cable should

be used.

Usecablewithroundcross-section.Acableouterdiameterof

5…9mm(0.2…0.35in)ensuresthesealeectofthecablegland.

Ifyouareusingcablewithadierentdiameterorcross-section,

exchange the seal or use a suitable cable gland.

We generally recommend the use of screened cable for HART multi-

drop mode.

On the instrument with cable entry ½ NPT and plastic housing there is

ametallic½"threadedinsertmouldedintotheplastichousing.

Caution:

No grease should be used when screwing the NPT cable gland or

steel tube into the threaded insert. Standard grease can contain

additives that corrode the connection between threaded insert and

Safety instructions

Voltage supply

Connection cable

Cablegland½NPT

1 2 ... 10 11 12 13 14 15 16 17 18 19 20 ... 63 64

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