Connection of the MSU120 Solar power supply

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2. Connection of the MSU120 Solar power supply

Connections are made using plug-in terminals according to the description on the power supply´s front name plate:

Description on the power supply´s front name plate

Fig. 2.1: Description on the power supply´s front name plate

  1. + terminal for positive pole

  2. – negative terminal (internally connected with negative terminal for connecting battery and with negative terminal for connecting load DC_OUT)

  3. earth terminals are connected to the metal casing of the source


Battery connection to terminals.


The source output has a common negative pole and two terminals with a positive output voltage which are internally disconnected according to the state of the accumulator to prevent deep discharge, or overcharging.


Auxiliary source output – not disconnected from the battery upon a drop in its voltage. Where necessary this can also be used as an input of another charging current (e.g. from the MS2000 network charger).


Output AUX.OUT/CHG is not protected with a current protection fuse.


Outputs with open collector with a common negative pole. The external voltage connected to these terminals cannot exceed the voltage at the output DC_OUT! Output switching is indicated by an LED lighting above the respective output.

By default:


Warning when battery voltage drops below 11.5 V


Low voltage from the solar panel


The serial port of the power supply is wired to a D-SUB connector (description of terminal like a DCE end device):

Pin. 1: DCD

(* internally connected DCD, DSR, DTR)

Pin 2: RXD

Data output from the power supply

Pin 3: TXD

Date input to the power supply

Pin 4: DTR

(* internally connected DCD, DSR, DTR)

Pin 5: Gnd

Signal ground – internally connected to the negative terminal of the power supply

Pin 6: DSR

(* internally connected DCD, DSR, DTR)

Pin 7: RTS

(** internally connected RTS, CTS)

Pin 8: CTS

(** internally connected RTS, CTS)

Pin 9:



The fuse on the front panel is connected into the battery circuit – it protects the battery and power supply against fault conditions whilst discharging and charging. In addition the source is protected by an electronic fuse which disconnects the source output (DC_OUT) if the source output current exceeds 6 A. After disconnecting the output as a result of overloading the power supply tries to connect the output every 20 s whilst testing whether any conditions for disconnecting the output still exist.


By pressing the START button the battery connection to the source output is left disconnected. However, if conditions for output disconnection persist this condition is automatically reversed (immediately in the case of overloading, and no later than within 2 minutes in the case of a low battery voltage).


Terminals for connecting an external temperature sensor. The sensor should be positioned, where possible, on the case of the charging accumulator. If installed with the accumulator simply connect the sensor to the power supply terminals. A KTY10 (2000 Ω/25 °C) temperature sensor is used.


The terminals cannot be connected through to other power supply terminals !!!

Temperature sensor characteristic: