User's Manual
MS3720
Slim Plug-In CT Transmitter with Isolated Single/Dual Output
Rev. 1.90
2
On Wiring:
Connections to the instrument should be made to the terminal
block. For assignment of the terminals, refer to section 6. The
recommended screwing torque is 0.8 to 1.0 Nm.
For lead wires, use a highly flexible stranded conductor. The
recommended nominal cross-section of the lead wire conductor
is 0.5 to 2.0 mm
2
. Additionally, the conductor for input lines
should have a cross-section of at least 2.0 mm
2
.
The connection of the lead wire to the terminal block should be
made with the insulated crimp terminal attached to the end of the
wire. Without the insulation, short circuit or electric shock may
occur. The recommended thickness of the crimp terminal is 0.7
to 1.0 mm.
Note that only up to two (2) crimp terminals can be connected to
one (1) terminal screw. In this case, the thickness of the crimp
terminal should be not greater than 0.8 mm. (As for the input
terminals, only one crimp terminal should be connected.)
It is recommended that ring crimp terminals be used for input
wiring to prevent them from easily coming off.
φ3.7
6.8
m
ax
.
3.4 max.
4.6 min.
To Avoid Erroneous Measurements:
In order to reduce the influence of noise, the input/output wire
and power supply wire should not be used in a same bundle or
same conduit. They should be installed separately with a
minimum distance of 200 mm.
Avoid wiring the signal lines in the vicinity of equipment
generating magnetic fields or electromagnetic waves, such as
electric motors and large-scale transformers. If inevitable,
anti-noise measures such as employment of shielded wires are
indispensable.
At least 30 minutes of warm-up is required prior to operation.
Any sensor or equipment to be connected to the instrument
should be selected in consideration of the input/output
impedance of the same. (For detailed specifications, refer to
section 4 or the relevant product specification sheet that can be
downloaded from our website at https://www.mtt.co.jp.)
On Shunt Resistor:
Check that the package contains a shunt resistor.
Before using the instrument, connect the shunt resistor across
the terminals specified below. If the instrument is used without
the shunt resistor, the secondary circuit of the CT will be opened,
which may cause the CT to burn out.
The shunt resistor supplied is not interchangeable. Be sure to
check that the serial numbers of the shunt resistor and the unit
are exactly the same.
Shunt Resistor
Special Notes for CE Marking:
The instrument is designed and manufactured to conform to the
following EMC and Low Voltage Directives:
EMC Directive (2014/30/EU)
- Standard conformity: EN61326-1:2013 Class A
Low Voltage Directive (2014/35/EU)
- Standard conformity: IEC61010-1
EN61010-1:2010/A1:2019
- Overvoltage Category: II
- Pollution Degree: 2
The instrument must be installed in a control panel.
The instrument maintains basic insulation between input and
output, and between output and FG. Prior to installation, check
that the insulation class of the instrument satisfies your system
requirements.
When the instrument is installed in a control panel, the measures
to be taken for CE marking conformity may vary with the type of
devices connected, wiring to the instrument or structure of the
control panel. Therefore, you should check that the control panel
as an overall system conforms to the CE marking regulations.
4. About the Product
The MS3720 accepts AC input from CT and provides isolated DC
output.
Features:
Pin and socket contacts are gold-plated (0.2
μ
m) to ensure high
reliability and long-term stability.
High dielectric strength of 2,000 VAC between input, [output 1,
output 2], power, and ground.
The power unit can deliver AC power ranging from 85 to 264V
steplessly without switching to meet varied power requirements.
Plug-in type for better maintainability
Drop-proof terminal screws for ease and safety of installation
Fuse installed in the power line as standard.
Installation Position
Typical Installation Example
