Release 04/02

Starting Up the Computing Unit

2.3Ensuring Readiness for Service

Measures for equipotential

Low-resistance grounding connections ensure that the user of the installation is protected against electric shock (for example, if a short-circuit occurs or if there are defects in the system). Moreover, they discharge interference transmitted by external power supply cables, signal cables or cables to I/O devices.

You should therefore create a low-resistance connection (a large surface acting as the contact) between the grounding point on the system housing and the central grounding point of the cabinet or the installation in which the computer is to be installed. The minimum cross-section should not be less than 5 mm2.

The grounding terminal is located on the side of the device and is identified by a

symbol.

Connection to the power supply

Power supply connection

Unit power plug

Figure 2-2 Power supply connection (device socket for non-heating appliances)

Caution

!The computing unit is equipped with a safety-tested power supply cable and may be connected only to a socket outlet with grounding contact.

Make sure that the socket outlet on the device or the socket outlet with grounding contact of the building wiring system is freely accessible and located as near to the device as possible.

The computing unit does not have a mains switch. To completely disconnect the PC from the mains power supply, you must pull the plug. This connection must be easily accessible.

If the PC is to be installed in a cabinet, a central disconnector must be provided.

Panel PC 670 Computing Unit, Equipment Manual

2-7

Page 31
Image 31
Siemens PC 670 manual Ensuring Readiness for Service, Measures for equipotential, Connection to the power supply