Electrical Connections; Electrical Terminals; Command Input (4-20 Ma) Connection; Figure 25: Terminal Diagram - Flowserve Logix 505+ User Instructions

7 ELECTRICAL CONNECTIONS

7.1 Electrical Terminals

HART 4-20 MA
Input +
Input -
Note: Tighten all ter-
minals 0.5 - 0.6 Nm

7.2 Command Input (4-20 mA) Connection

The Logix 505+ is reverse polarity protected, however, verify polarity
when making field termination connection. Wire 4-20 mA current
source to the input terminal labeled "4-20mA INPUT". Tighten termi-
nals 0.5 to 0.6 Nm torque. See Figure 25: Terminal Diagram.
7.2.1 Compliance Voltage
Output compliance voltage refers to the voltage limit the current
source can provide. A current loop system consists of the current
source, wiring resistance, barrier resistance (if present), and the Logix
505+ impedance.
The Logix 505+ requires that the current loop system allow for a 6
VDC drop across the positioner at maximum loop current. The oper-
ating current range is from 3.8 to 24 mA.
In order to determine if the loop will support the Logix 505+, perform
the calculation in the following equation. The Available Voltage must
be greater than 6 VDC in order to support the Logix 505+. Also, see
Table 1: Input Signal.
Logix 505+ Digital Positioners FCD LGENIM0109-03-A4 – 09/15
®

Figure 25: Terminal Diagram

Equation 1
Available Voltage =Controller Voltage (Current
Current x (R
max
Current = 20mA
max
R = 3 00Ω
barrier
R = 25Ω
wire
Available Voltage = 19 V - 0.020 A × (300Ω + 25Ω)
Available Voltage = 12.5 V
The available voltage (12.5 V) is greater than the required voltage (6.0
V) therefore; this system will support the Logix 505+. The Logix 505+
has an input resistance equivalent to 500 Ω at a 20 mA input current.
a
CAUTION: The current must always be limited for 4-20 mA oper-
ation. Never connect a voltage source directly across the Logix
505+ terminals. This could cause permanent circuit board damage.
max
+ R )
barrier wire
) -
23
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