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2.2 Power Connections
Make sure that all local and national electrical standards are met when the installing the MMI.
Contact your local authorities to determine which codes apply.
2.2.1 Power Requirements
Power
The MMI can be powered by DC power only. The specified voltage
range is +12 to 27 Volts DC. This insures compatibility with most DC
systems. The power conditioning circuitry inside the unit is accom-
plished by a switching power supply. Due to the nature of switching
power supplies, a wide range of over and under voltages may be used
without adversely affecting the unit.
Fusing
Requirements
It is recommended that all input power lines be protected from
incorrect wiring or product failure by a 400 mA fuse or a breaker. If the
display does not come on within 2 seconds of power up, remove
power. An internal diode will prevent damage if the polarity of the DC
power is incorrect. Check wiring to insure proper connections and try
to power up again.
Caution
Strain Relief
Adequate strain relief must be provided for the power connector, to
ensure that vibration or the disturbance of cables during maintenance
does not cause the connector to pullout. Retention of the power cables
by a tye-wrap onto the trunking, or an adhesive pad mounted tye-wrap
point is normally suitable.
Caution
High Voltage
Connecting high voltages or AC power mains to the DC input will
make the MMI unusable and may create an electrical shock hazard to
personnel. Such a failure or shock could result in serious personal
injury, loss of life and or equipment damage.
DC voltage sources should provide proper isolation from main AC
power and similar hazards.
Caution
Emergency Stop
A Hard wired EMERGENCY STOP should be fitted in any system
using the MMI to comply with ICS Safety Recommendations.
Caution Supply
Voltage Condition
Do not power the MMI and inductive DC loads, or input circuitry to the
PLC with the same power supply. The 24 VDC output from some
PLC's may not have enough current to power the MMI.
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