1 Terminal Block
MMB-8
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MMB50A MMB75A
Frame ground
AC(L)
AC(N)
LED(V1)
Output voltage adjustable potentiometer(V1)
V1 Output
G1(V1) GND
V2 Output
NC
G1(V2) GND
2 Function
2.1 Input voltage range
2.2 Inrush current limiting
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The range is from AC85V to AC132V or DC110V to DC170V.
AC input voltage must have a range from AC85V to AC132V for
normal operation. If the wrong input is applied, the unit will not op-
erate properly and/or may be damaged.
In cases that conform with safety standard, input voltage range is
AC100-AC120V(50/60Hz).
If a switch on the input side is installed, it has to be the one han-
dling the input inrush current.
The thermistor is used for protection from inrush current. When
power is turned ON/OFF repeatedly within a short period of time,
it is necessary to have enough time for power supply to cool
down.
The thyristor technique is used for protection from inrush current.
When power is turned ON/OFF repeatedly within a short period of
time, it is necessary to have enough time between power ON and
OFF to operate resistance circuit for inrush current.
Inrush current limiting is built-in.
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MMB50A
MMB75A
2.3 Overcurrent protection
2.4 Overvoltage protection
2.5 Output voltage adjustment range
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Overcurrent protection is built-in and comes into effect at over
105% of the rated current. Overcurrent protection prevents the
unit from short circuit and overcurrent condition of less than 20
sec. The unit automatically recovers when the fault condition is
cleared.
When the overcurrent/short circuit condition continues more than
20 seconds, it may damage devices inside the power supply.
The power supply which has a current foldback characteristics may
not start up when connected to a nonlinear load such as a lamp,
motor or constant current load. See the characteristics below.
In V1 & V2, The overvoltage protection circuit is built-in and co-
mes into effect at 115 - 140% of the rated voltage. The AC input
should be shut down if overvoltage protection is in operation. The
minimum interval of AC recycling for recovery is 2 minutes.
Please avoid applying the over-rated voltage to the output termi-
nal. Power supply may operate incorrectly or fail.In case of oper-
ating a motor etc. , please install an external diode on the output
terminal to protect the unit.
Adjustment of output voltage for V1 is possible by using potenti-
ometer.
Output voltage is increased by turning potentiometer clockwise
and is decreased by turning potentiometer counterclockwise.
The recovery time varies depending on input voltage.
When potentiometer is over-turned clockwise, overvoltage protec-
tion function activates. To set up output voltage, first turn potenti-
ometer counterclockwise to the end, then turn back clockwise
gradually until reaching the level of required voltage.
Remarks:
MMB
A
Output
V
olt
age
[V]
V
Load factor [%]
100
Fig. 2.1 Current foldback characteristics
Note: In case of nonlinear load, the output is locked out at A point.
: Load characteristics of power supply.
: Characteristics of load (lamp, motor, constant current load, etc.).
Instruction Manual
AC-DC Power Supplies Enclosed type
June 29, 2011
