Siemens S7-400 Connecting the Load Voltage Ground, Mode Connection of Load Voltage

Wiring the S7-400

Connecting the Load Voltage Ground

Many output modules require an additional load voltage to switch the actuators. Two different modes are possible for this load voltage:

•Non-isolated operation

•Floating operation

The following table shows how the load voltage ground is connected in the individual modes.

Table 4-3		Grounded connection load voltage
		Mode	Connection of Load Voltage
Non-isolated operation
•	Grounded configuration		to the reference point of the rack; metallic connection
			between frame element and chassis ground must be
			fitted.
•	Ungrounded configuration		to the reference point of the rack; metallic connection
			between frame element and chassis ground must be
			fitted.
Floating operation
•	Grounded and ungrounded		Left open or to any point, but not to protective ground
	configuration		or reference potential M of operating voltages

The following figure shows how the load voltage ground is connected for non-isolated operation.

Metallic connection, remove for ungrounded configuration

Ground terminal for load voltage

Figure 4-7 Grounded connection load voltage

4-14	Automation System S7-400	Hardware and Installation
		A5E00850741-01