Siemens SIMATIC S7-400 Reference Manual page 18

General specifications
1.1 Standards, certificates and approvals
Example
The Varta 4022 battery together with a 1.5 m long cable and a Leonhardy 02-02.1500 plug
meet these conditions.
FM Approval
Factory Mutual Approval Standard Class Number 3611, Class I, Division 2,
Group A, B, C, D.
Temperature class: T4 at 60° C ambient temperature
Personal injury or property damage can result.
In hazardous areas, personal injury or property damage can result if you create or break an
electrical circuit during operation of an S7-400 (for example, by means of plug-in connections,
fuses, switches).
Do not create or break live electrical circuits unless you are certain there is no danger of
explosion.
When used in FM conditions, the S7-400 must be fitted in an enclosure that corresponds to
at least IP54 in accordance with EN 60529.
NEC (National Electric Code) and CEC (Canadian Electric Code) requirements for Hazardous
Locations for battery power supply for CPUs
The backup voltage for a CPU must be supplied over a non-incendive plug connection. The
figure below shows such a plug connection.
(1)
(2)
Figure 1-2
The following conditions apply to the performance characteristics of this connection:
Voc (no load voltage) = 15 V
Isc (short-circuit current)= 50 mA
Ca = Battery/voltage supply capacity
La = Battery/voltage supply inductance
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WARNING
1
Battery or supply voltage
CPU with "Ext. Batt." connector
Back-up voltage supply
2
Vmax = 15 V
Imax = 50 mA
Ci = 25 nF maximum
Li = 2 mH maximum
S7-400 Automation System Module Data
Reference Manual, Ausgabe 11/2016, A5E00850736-08