Wachendorff LD4A05P0 Current-/voltage display LD4A05P0 LD4A05P0 Scheda Tecnica

Although this meter is designed with a high degree of immunity to Electro-

Magnetic Interference (EMI), proper installation and wiring methods must be 
followed to ensure compatibility in each application. The type of the electrical 
noise, source or coupling method into the meter may be different for various 
installations. The meter becomes more immune to EMI with fewer I/O 
connections. Cable length, routing, and shield termination are very important 
and can mean the difference between a successful or troublesome installation. 
Listed below are some EMC guidelines for successful installation in an 
industrial environment.

1. The meter should be properly connected to protective earth.

2. Use shielded (screened) cables for all Signal and Control inputs. The shield 

(screen) pigtail connection should be made as short as possible. The 
connection point for the shield depends somewhat upon the application. 
Listed below are the recommended methods of connecting the shield, in order 
of their effectiveness.
a. Connect the shield only at the panel where the unit is mounted to earth 

ground (protective earth).

b. Connect the shield to earth ground at both ends of the cable, usually when 

the noise source frequency is above 1 MHz.

c. Connect the shield to common of the meter and leave the other end of the 

shield unconnected and insulated from earth ground.

3. Never run Signal or Control cables in the same conduit or raceway with AC 

power lines, conductors feeding motors, solenoids, SCR controls, and 
heaters, etc. The cables should be ran in metal conduit that is properly 
grounded. This is especially useful in applications where cable runs are long 
and portable two-way radios are used in close proximity or if the installation 
is near a commercial radio transmitter.

4. Signal or Control cables within an enclosure should be routed as far as 

possible from contactors, control relays, transformers, and other noisy 
components.

5. In extremely high EMI environments, the use of external EMI suppression 

devices, such as ferrite suppression cores, is effective. Install them on Signal 
and Control cables as close to the unit as possible. Loop the cable through the 
core several times or use multiple cores on each cable for additional protection. 
Install line filters on the power input cable to the unit to suppress power line 
interference. Install them near the power entry point of the enclosure. The 
following EMI suppression devices (or equivalent) are recommended:

Ferrite Suppression Cores for signal and control cables:

Fair-Rite # 0443167251 (RLC# FCOR0000)
TDK # ZCAT3035-1330A
Steward # 28B2029-0A0

Line Filters for input power cables:

Schaffner # FN610-1/07 (RLC# LFIL0000)
Schaffner # FN670-1.8/07
Corcom # 1 VR3

Note: Reference manufacturer's instructions when installing a line filter.

6. Long cable runs are more susceptible to EMI pickup than short cable runs. 

Therefore, keep cable runs as short as possible.

7. Switching of inductive loads produces high EMI. Use of snubbers across 

inductive loads suppresses EMI.

Snubber: RLC# SNUB0000.

Electrical connections are made via pluggable terminal blocks located inside 

the meter. All conductors should conform to the meter's voltage and current 
ratings. All cabling should conform to appropriate standards of good installation, 
local codes and regulations. It is recommended that the power supplied to the 
meter (DC or AC) be protected by a fuse or circuit breaker. When wiring the 
meter, compare the numbers on the label on the back of the meter case against 
those shown in wiring drawings for proper wire position. Strip the wire, leaving 
approximately 0.4" (10 mm) bare lead exposed (stranded wires should be tinned 
with solder.) Insert the lead under the correct screw clamp terminal and tighten 
until the wire is secure. (Pull wire to verify tightness.) Each terminal can accept 
up to one #14 AWG (2.55 mm) wire, two #18 AWG (1.02 mm), or four #20 
AWG (0.61 mm).

Internal removable terminal 

blocks are used for power and 
signal wiring. Access to 
terminal blocks is through 
conduit fittings. Remove end 
plates with ¼" nut driver. For 
LD4 versions, all wiring is on 
right side of unit. For LD2 
versions, power and relay 
wiring is on the right side and 
the input, serial, DC out and 
user input is on the left side.

Connect drain wire from 

shielded cable(s) to screw on 
side plate for proper grounding.

Front

TBA

3

2

1

Front

TBB

46

5

13

2

TBC

TBD

3

1

2

4

56

RANGE SELECT

1

23

4

5

Front

TBA

3

2

1

46

5

3

2

1

TBB

RANGE SELECT

6

5

4

23

1

TBC

5

34

2

1

TBD

The power wiring is made via the 3 position terminal block (TBA) located 

inside the unit (right side). The DC out power is located: LD2 - left side, LD4 
- right side

USER COMM

+ EXC

6

4

TBC

Terminal 4: + 24 VDC OUT

Terminal 6: User Common

Terminal 1: VAC/DC +

Terminal 2: VAC/DC -

Terminal 3: Protective Conductor  

  

 Terminal

1

2

L1

L2

3

TBA

+

-