Yokogawa MH1 User Manual

User’s
Manual

Model MH1
Isolator

IM 77J04H01-01E

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

IM 77J04H01-01E

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.

4.1 Wall Mounting

Remove the stoppers (top and bottom) from the product and pull out
the main unit from the socket. Fix the socket on the wall using two M4
screws. Next, insert the main unit into the socket and fasten the main
unit with the stoppers (top and bottom).

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

Main unit

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.

IMPORTANT

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

<Mounting Dimensions>

Socket

2-ø4.5 or 2-M4

NOTE

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

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:

● MH1: 1

● Receiving resistor (for current input): 1

● Spacer (used for DIN rail mounting): 1

● User’s Manual (this manual: IM 77J04H01-01E): 1 copy

40±0.2

DIN rail

3. GENERAL

This plug-in type isolator receives DC current or DC voltage signals to
convert them into isolated DC current or DC voltage signals.

4. MOUNTING METHOD

Pitch: 55 or more

5 or more

(51)

Push

Mounting

screws

(85)

Fit into here

DIN rail

Spacer

Stopper

Socket

Unit: mm

Note:
(1) More than 5 mm interval is

required for side-by-side
close mounting.

(2) Use the supplied spacer for

DIN rail mounting to keep 5
mm interval.

(Rear of the socket)

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.

Slide lock

4.3 Using a Duct

When using a wiring duct, install the duct at leaset 20 mm away from
the top and bottom faces of the main unit.

5. INSTALLATION LOCATIONS

g

>

t

)

t

● 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 M3.5 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.

Receivingl resistor

for current input

Power Supply

GND

6

L+

7

N–

8

<External Receivin

Input ragne
10 to 50 mA DC
4 to 20 mA DC
0 to 20 mA DC
0 to 16 mA DC

Resistor for Current Input

Resistance

Part No. Input ragne

100 

RES-100

250 

RES-250

2 to 10 mA DC
0 to 10 mA DC
1 to 5 mA DC
0 to 1 mA DC

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.

6) 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.

Input signal

+

3

Ri

4

–

: External receiving resistor
for current inpu
(See the table below.

Output

+

1

–

2

Resistance

500 

1k 

Part No.

RES-500

RES-01K

7. PART NAMES OF FRONT PANEL

The figure below shows the MH1 with its front panel (cover) being
open.

Zero-adjustment volume

Span-adjustment volume

Power indicator lamp

Lit during power on

8. 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

2

specified performance.

8.1 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

8.2 Calibration Procedure

(1) Connect the instruments as shown below.
(2) Use the DC voltage/current standard and apply input signals

equivalent to 0, 25, 50, 75, 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.

Receiving resistor

for current inpu

Input



3

DC voltge/
current

Ri

Power supply

GND

6

L

7

N

8

standard

4



Ri

: External receiving resistor for

current input (See chapter 6.)

Output



1

Digital

Ro

multimater



2

Ro

: 250  precision resistor

for current output

2

IM 77J04H01-01E 2nd Edition June 01,2004-00