MSA SUPREMATouch MCP 20 Operating Manual Download Page 17

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System Concept

SUPREMATouch

INT Terminals (Internal Power Supply, 24 VDC 250 W)

• Connection for voltage supply from an internal rack power supply or an external power supply

unit.

• Power supplied to all rack units and the sensors.
• Internal power supply unit (MSP module) has a supply voltage input of 85–265 VAC

(47–63 Hz) or 120–330 VDC.

• If the rack power supply unit cannot supply enough power, the sensors, modules or relays must

be supplied by external power supply units.

• The internal rack power supply can be omitted if, because of a high power requirement or a

redundant design, the power is being supplied by an external power supply via the INT termi-
nals.

• Maximum supply current of 20 A.

BAT Terminals (Backup Battery Power Supply)

• Backup battery power supply for all units of a rack (21 –28 VDC).
• In the case of failure of internal and/or external power supply, the backup battery power supply

will supply power to the system.

• Maximum supply current of 20 A.

Power Supply Plans

All of the system cards and the sensors can be supplied from each of the 3 pairs of terminals
connections. A voltage changeover switch is provided on each system card, which ensures that
only one of the voltages being applied is accepted. Various power supply plans are available to
suit the number and type of sensors and/or the required degree of redundancy in the power
supply.
If the internal rack power supply unit is not sufficient to power all the sensors, an external unit must
be provided. The internal unit must then be disconnected. A redundant power supply is then
provided by external units via the BAT or INT terminals.

Supply Plan A: Internal Power Supply Unit

All of the units of the system and the sensors are supplied by the rack power supply unit (INT
terminals). This variant is used when power supply redundancy is not required and the power
which can be supplied by the unit installed in the rack (250 W) is sufficient to supply all of the rack
modules and the connected sensors.

Supply Plan B: External Power Supply Unit

All system modules housed in the rack and the sensors are supplied by the external power supply
unit (EXT terminals). This variant is used when power supply redundancy is not required and the
power of the unit installed in the rack (250 W) is not sufficient to supply all of the system modules
and the connected sensors. A maximum of 20 A can be supplied across the terminals (480 W
system power).

Supply Plan C: Internal Power Supply Unit + Battery

All units of the system and the sensors are supplied by the rack power supply unit (INT terminals)
or by the backup power supply (BAT terminals). This variant is used when there must be redun-
dancy in the power supply and the power of the unit installed in the rack (250 W) is sufficient for
all rack modules and the connected sensors.

Supply Plan D: External Power Supply Unit + Battery

All modules of the system and the sensors are supplied by the external power supply unit
(EXT terminals) or by the backup power supply (BAT terminals). This variant is used when the
power supply must be redundant and the power that can be supplied by the unit installed in the
rack is not sufficient to supply the system modules and the connected sensors. A maximum of
20 A can be supplied across the terminals (480 W system power).

2.8

Safety Concept

The individual functional modules are connected to each other by a CAN bus. The CAN bus is
designed to be virtually error-proof. Every module can detect errors on the bus and handle them
appropriately. The probability of an undiscovered communications error on the bus is 4.7 * 10

-14

Error statuses on the CAN bus are indicated on the D OPERATION unit (MDO module).