User's Manual
MS3720
Slim Plug-In CT Transmitter with Isolated Single/Dual Output
Rev. 1.90
3
Specifications
5. External Dimensions & Terminal Assignments
6. Terminal Connection Diagram
Shunt Resistor
Bracket
Terminal
No.
Bracket
Note: For the single output model, the OUTPUT2 shown should be
interpreted as N.C.
7. Terminal Connection
The following steps should be taken prior to the connection.
8. Power Line Connection
The terminals for power supply connection (
①
and
②
) are covered
with a plastic plate for safety (see Fig. 1).
Open the cover plate and connect the power lines to the terminals
(see Fig. 2).
Return the cover plate to its original position (see Fig. 3).
4
5
1
2
P/+
N/-
4
5
4
5
Terminal Block
Cover
Note: For your safety, do not make any electrical connections or
disconnections with power supplied to the instrument. Make
sure that all terminal screws are properly tightened each time
you finish the tightening.
Input
Resistance
5A AC input: 2m
Ω
(Shunt resistor)
1A AC input: 10m
Ω
(Shunt resistor)
Allowable Input
Current
Continuous: 120% of the rated input value
Instantaneous: 10 times the rated input value
(within 3 seconds)
Crest Factor 3
max.
Allowable
Output Load
Voltage output:
1V span and up: 2mA max.
10mV: 10k
Ω
min.
100mV: 100k
Ω
min.
Current output:
Single current output:
750
Ω
max. (for 4-20mA output)
Dual current output:
Output 1: 550
Ω
max. (for 4-20mA output)
Output 2: 350
Ω
max. (for 4-20mA output)
Zero Adjustment
Approx. ±5% of span.
(Adjustable by the front-accessible trimmer.)
Span
Adjustment
Approx. ±5% of span.
(Adjustable by the front-accessible trimmer.)
Accuracy Rating
Better than ±0.25% of span with at least 10%
input (at 25°C±5°C)
Temperature
Effect
Better than ±0.2% of span per 10°C change in
ambient.
Response Time 400ms max. (0-90%) with a step input at 100%
Insulation
Resistance
100M
Ω
min. (@ 500V DC) between input,
output 1, output 2, power, and ground.
Dielectric
Strength
Input, [Output 1, Output 2] / [Power, Ground]:
2000V AC for 1 minute (Cutoff current: 0.5mA)
Power / Ground: 2000V AC for 1 minute (Cutoff
current: 5mA)
Output 1 / Output 2: 500V AC for 1 minute
(Cutoff current: 0.5mA)
Surge
Withstand
Capability
Tested as per ANSI/IEEE C37.90.1-1989.
Storage
Temperature
-10 to 60°C
(1) Loosen the terminal screw.
(2) Insert the tip of a
screwdriver bit beneath
the washer and push it
up to make ample room
to receive a cable.
Fig. 1
Fig. 2
Fig. 3
1
2
4
5
6
7
8
9
10
11
