Page 3-2
FPU-32 Feeder Protection Unit
Rev.
2-A-103014
System
Wiring
3.2 W
IRING
C
ONNECTIONS
3.2.1 FPU-32 C
ONNECTIONS
The FPU-32 wire-clamping terminal blocks accept 24
to 12 AWG (0.2 to 2.5 mm
2
) conductors. These terminal
blocks unplug to allow the FPU-32 to be easily replaced.
3.2.1.1 S
UPPLY
V
OLTAGE
Derive supply voltage from the line side of the breaker
or from an independent source. Connect supply voltage
to terminals 2 and 3 (L1 and L2/N) as shown in Fig. 3.1.
In 120-Vac systems, L2/N is designated as the neutral
conductor. For direct-current power supplies, use L1 for
the positive terminal and L2/N as the negative terminal.
Ground terminal 8 (
).
3.2.1.2 CIM I
NPUT
Connect the FPU-32 to the MPU-CIM as shown in
Figs. 3.6 and 3.7 using the cable provided with the
MPU-CIM.
3.2.1.3 D
IGITAL
I
NPUT
A 24-Vdc digital input is provided on terminals 25 and
26. This input is polarity sensitive. For a logical 1,
terminal 26 must be positive with respect to terminal 25.
See Section 4.2.6.
The current-limited 24-Vdc source (terminals
27 & 31) can be used for the digital input.
3.2.1.4 A
NALOG
O
UTPUT
The analog output is switch selectable as self powered
or loop powered.
For the self-powered connection, set the L/S switch to
the S position. The self-powered connection is shown in
Fig. 3.2 (a). The analog output is referenced to the I/O
module supply, terminal 27.
For the loop-powered connection, set the L/S switch to
the L position. The loop-powered connection is shown
in Fig. 3.2 (b). In loop-powered operation, the analog-
output is isolated from all other FPU-32 terminals.
a) SELF POWERED (S POSITION)
AA
AB
24
23
RECEIVER
TERMINATION
b) LOOP POWERED (L POSITION)
AA
AB
+
-
LOOP
SUPPLY
24
23
RECEIVER
TERMINATION
FIGURE 3.2 Analog-Output Connections.
3.2.1.5
PTC
or
RTD
I
NPUT
The temperature-sensor input on the FPU-32 can be
configured for either PTC or Pt100 RTD operation as
shown in Fig. 3.3.
a) PTC
b) Pt100 RTD
19
18
17
TC
TB
TA
+t˚
19
18
17
TC
TB
TA
t˚
FIGURE 3.3 Temperature-Sensor Connections.
3.2.1.6 I/O M
ODULE
C
OMMUNICATIONS
The I/O module communications interface is used to
support optional modules.
At the publication date, no optional FPU-32 modules
were available. The 24-Vdc supply can be used to power
the digital input as outlined in Section 4.2.6.
I/O module communication is based on the two-wire
multi-drop TIA-485 standard but uses a proprietary
protocol. Overall line length must not exceed 1.2 km
(4,000’). For line lengths exceeding 10 m (33’), 150-
terminations are required at the cable ends. See Fig. 3.4.
N
OTE:
I/O communication is shared with the display.
Incorrect wiring can cause the display and keypad to
freeze.
+
+
+
-
-
-
FPU-32
31
30
29
28
27
3
R
t
RED
GREEN
WHITE
BLACK
I/0
MODULE
R
t
NOTES:
1. INTERCONNECT CABLE BELDEN 3124A
OR EQUIVALENT.
2. R
t
= 150 OHMS, 1/4 WATT. REQUIRED FOR LINE
LENGTHS EXCEEDING 10 M (33’).
+24V
+
SH
-
0V
I/0
MODULE
FIGURE 3.4 I/O Module Connection Diagram.
