Yokogawa VJA5 User Manual

User’s
Manual

Model VJA5
Distributor
(with Square Root Extractor)
(Isolated Single-output and

IM 77J01A05-01E

Please read through this User’s Manual before use for correct handling.
Please keep this User’s Manual for future reference.

Isolated Dual-output Types)

IM 77J01A05-01E

1st Edition Jul. 2003 (MC)

2nd Edition June 2004 (YK)

Network Solutions Business Divisiion

2-9-32, Naka-cho Musashino-shi, Tokyo 180-8750 Japan
Phone: [phone] Facsimile: [phone]

1. CAUTIONARY NOTES FOR SAFE USE OF THE PRODUCT

This User’s Manual should be carefully read before installing and oper­ating the product. The following symbol is used on the product and in
this manual to ensure safe use.

This symbol is displayed on the product when it is
necessary to refer to the User’s Manual for information on
personnel and instrument safety. This symbol is displayed
in the User’s Manual to indicate precautions for avoiding
danger to the operator, such as an electric shock.

The following symbols are used only in this manual.

4.1 Wall Mounting

Loosen the main unit-fixing screw of the product and pull out the main
unit from the socket. Fix the socket on the wall with screws. Next, in­sert the main unit into the socket and fasten the main unit with the main
unit-fixing screw.

Output-1

Zero-adjustment volume

Span-adjustment volume

Output-2

Zero-adjustment volume

Span-adjustment volume

IMPORTANT

Indicates that operating the hardware or software in a
particular manner may cause damage or result in a system
failure.

<Mounting Dimensions>

NOTE

Draws attention to essential information for understanding
the operations and/or functions of the product.

Main unit

29.5 or more
22±0.2

59±0.3

Mounting

screws

Main
unit-fixing
screw

2-M4 or 2-ø4.5 or more

Socket

Threaded hole for
fixing the main unit

Unit: mm

2.

CHECKING PRODUCT SPECIFICATIONS AND PACKAGED ITEMS

(1) Checking the Model and Product Specifications

Check that the model and specifications indicated on the nameplate
attached to the side face of the main unit are as ordered.

4.2 DIN Rail Mounting

Insert a DIN rail into the upper part of the DIN rail groove on the rear of
the socket, and then slide the slide lock at the lower part of the socket
upwards until the socket is fixed into position as shown below.

(2) Packaged Items

Check that the packing carton contains the following items:

● VJA5: 1

● Tag number label: 1 sheet

● User’s Manual (this manual: IM 77J01A05-01E): 1 copy

DIN rail

3. GENERAL

This plug-in type distributor is used in combination with a two-wire type
transmitter to calculate the square root of 4 to 20 mA DC input signals
from the transmitter and then convert them into isolated DC current or
DC voltage signals.

4. MOUNTING METHOD

NOTE

Insert/pull out the main unit into/from the socket vertically
to the face of socket. Otherwise the terminals are bent and
it may cause a bad contact.

4.3 Mounting Using a Multi-mounting Base

When using a multi-mounting base, see the User’s Manual for VJCE
(VJCE Mounting Base).

4.4 Using a Duct

When using a wiring duct, install the duct at leaset 30 mm away from
the top and bottom faces of the main unit.

Fit into here

DIN rail

Push

(Rear of the socket)

DIN rail

Slide lock

5. INSTALLATION LOCATIONS

● Avoid the following environments for installation locations:
Areas with vibration, corrosive gases, dust, water, oil, solvents, di­rect sunlight, radiation, a strong electric field, and/or a strong
magnetic field

● If there is any risk of a surge being induced into the power line
and/or signal lines due to lightning or other factors, a dedicated
lightning arrester should be used as protection for both this unit
and a field-installed device.

6. EXTERNAL WIRING

WARNING

To avoid the risk of an electric shock, turn off the power
supply and use a tester or similar device to ensure that no
power is supplied to a cable to be connected, before carring
out wiring work.

Wiring should be connected to the terminals on the socket of the prod­uct. The terminals for external connections are of M3 screws. Use
crimp-on terminal lugs for connections to the terminals.

● Recommended cables: A nominal cross-sectional area of 0.5 mm
or thicker for signal cables, and that of 1.25 mm2 or thicker for
power cables.

Example to construct

Intrinsically Safe System

using Zener Barrier

1

+

3

4

–

PS+

+

–

–

COM

1

3

4

3 2

1

56

4

789

1011

Power supply

1110 8

GND

N–

L+

When using

internal

power supply

PS+

1

+

–

–

3

4

COM

Output-2

+

2

–

5

Output-1

+

7

–

9

When using

external

power supply

7. MAINTENANCE

The product starts running immediately when the power is turned on;
however, it needs 10 to 15 minutes of warm-up before it meets the
specified performance.

7.1 Calibration Apparatus

● A DC voltage/current standard (Yokogawa 7651 or the equivalent)

● A digital multimater (Yokogawa 7561 or the equivalent)

● A precision resistor of 250  ± 0.01%, 1 W

7.2 Calibration Procedure

(1) Connect the instruments as shown below. First adjust the output-1

signal and then the output-2 signal.

(2) Use the DC voltage/current standard and apply input signals

equivalent to 0, 6.25, 25, 56.25, and 100% of the input span to the
product. Check to see the corresponding output voltages are 0,
25, 50, 75, and 100% respectively and within the specified accu­racy rating. “R” is used for current output.

● If the output signals are out of the accuracy rating range, adjust
the output signal level using the zero and span adjustment vol­umes on front face of the product.

3 2

L

5

1011

1110 8

N

1
4

2

R

5

789

7

R

9

R: 250  precision resistor
for current output

GND

Output-2



Digital
multimater



Output-1



Digital
multimater



2

Input

With SINK current

DC voltge/
current
standard

Without SINK current

DC voltge/
current
standard



1



3



3



4

6

Power supply

IMPORTANT

●

The power line and input/output signal lines should be
installed away from noise-generating sources. Other
wise accuracy cannot be guaranteed.

●

The grounding resistance must be 100 Ω (JIS Class D
grounding). The length and thickness of the grounding
cable should be as short and thick as possible. Directly
connect the lead from the ground terminal (terminal no.

8) of the product to the ground. Do not carry out daisy­chained inter-ground terminal wiring.

●

Use of the product ignoring the specifications may
cause overheating or damage. Before turning on the
power, ensure the following:
(a) Power supply voltage and input signal value applied

to the product should meet the required
specifications.

(b) The external wiring to the terminals and wiring to

ground are as specifications.

●

Do not operate the product in the presence of
flammable or explosive gases or vapors. To do so is
highly dangerous.

●

The product is sensitive to static electricity; exercise
care in operating it. Before you operate the product,
touch a nearby metal part to discharge static electricity.

2

IM 77J01A05-01E 2nd Edition June 01,2004-00