HP T100 Spécifications télécharger pdf (Page 16)

SECTION II ELECTRICAL

Installation Notes on Ametek UHP 4-20 mA Transmitter

Wiring Notes: Bendix® compatible connector

1. Hookup: The 4-20 mA transmitter utilizes a 2 wire system. Current flowing from a

power supply into Connector Pin A is used to power the transmitter. Current flowing

out of Connector Pin D may be connected to a 4-20 mA input of a loop indicator, for

example, or across a loop resistor. The return from the loop indicator or loop resistor

should be tied to the negative connection of the power supply. It is important to

understand the voltage drop of any loop device added in series with the current flow.

For example, many loop indicators or PLC’s may take up to 5 Vdc each to operate (at

full scale current of 20 mA.). The transmitter should have at least 12 Vdc across

Connector Pin A and Pin D at all times. Thus in this example, with the transmitter

needing 12 Vdc to operate and the loop indicator and PLC each requiring 5 Vdc, the

power supply should be set above 22 Vdc. A 24 Vdc supply is often used when

operating multiple loop devices.

2. Grounding and Shielding: The Bendix® compatible connector pin C may be used to

connect to the transmitter case. For use in high EMI fields, the user may wish to tie a

mating cable shield or drain wire to this pin to provide shielding to the transmitter

case. With some mating connectors, it is not necessary to tie the shield or drain wire

to pin C if the mating cable has a clamp which can be crimped over the drain wire and

the act of mating the two connectors provides shield continuity. A separate wire may

also be tied to pin C to bring the case ground connection to another location. In many

cases, the mating cable shield can be tied to the gas cabinet case, providing an

excellent shield to EMI. In some cases, however, ground loops may prevent this type

of hookup so caution is advised.

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HP T100 Spécifications Page 16