One power supply module is required per rack.
Exception:
With interfaces with current transfer, the power supply module in the central controller also supplies all modules in the expansion units.

The load voltage for supplying sensors and actuators must be made available separately.

There are also power supplies to make both the standard system and the H system fail-safe (redundant power supplies).

Siemens Power Supply S7-400 Product Specifications:

Article number	6ES7407-0DA02-0AA0	6ES7407-0KA02-0AA0	6ES7407-0KR02-0AA0	6ES7407-0RA02-0AA0
	POWER SUPPLY PS407, 120/230V UC,5V DC/4A	PS407 POWER SUPPLY,120/230V UC,5V DC/10A	POWERSUPP.PS407,UC120/230V,DC5V/10A,RED.	PS407 POWER SUPPLY,120/230V UC,5V DC/20A
Supply voltage
Rated value (DC)
● 120 V DC	Yes	Yes	Yes	Yes
● 230 V DC	Yes	Yes	Yes	Yes
Rated value (AC)
● 120 V AC	Yes	Yes	Yes	Yes
● 230 V AC	Yes	Yes	Yes	Yes
Line frequency
● Rated value 50 Hz	Yes	Yes	Yes	Yes
● Rated value 60 Hz	Yes	Yes	Yes	Yes
● permissible range, lower limit	47 Hz	47 Hz	47 Hz	47 Hz
● permissible range, upper limit	63 Hz	63 Hz	63 Hz	63 Hz
Mains buffering
● Mains/voltage failure stored energy time	20 ms	20 ms	20 ms	20 ms
● Mains buffering according to NAMUR recommendation	Yes	Yes	Yes	Yes
Input current
Rated value at 120 V DC	350 mA	1 A	1 A	1.4 A
Rated value at 230 V DC	190 mA	0.5 A	0.5 A	0.7 A
Rated value at 120 V AC	0.42 A	0.9 A	0.9 A	1.4 A
Rated value at 230 V AC	0.22 A	0.5 A	0.5 A	0.7 A
Inrush current, max.	8.25 A; Full width at half maximum 5 ms	63 A; Full width at half maximum 1 ms	63 A; Full width at half maximum 1 ms	88 A; Full width at half maximum 1.1 ms
Leakage current, max.	3.5 mA	3.5 mA	3.5 mA	3.5 mA
output voltage / header
Type of output voltage	DC	DC	DC	DC
Rated value (DC)
● 5 V DC	Yes	Yes	Yes	Yes
● 24 V DC	Yes	Yes	Yes	Yes
Output current
for backplane bus (5 V DC), max.	4 A; no base load required	10 A; no base load required	10 A; no base load required	20 A; no base load required
for backplane bus (24 V DC), max.	0.5 A; idling-proof	1 A; idling-proof	1 A; idling-proof	1 A; idling-proof
Short-circuit protection	Yes	Yes	Yes	Yes
Power
Active power input, typ.	52 W	95 W	95 W	158 W
Power loss
Power loss, typ.	20 W	20 W	20 W	35 W
Battery
Backup battery
● Backup battery (optional)	Yes; 1x lithium AA; 3.6 V / 2.2 Ah	Yes; 1x lithium AA; 3.6 V / 2.2 Ah	Yes; 1x lithium AA; 3.6 V / 2.2 Ah	Yes; 1x lithium AA; 3.6 V / 2.2 Ah
Hardware configuration
Slots
● required slots	1	2	2	2
Potential separation
primary/secondary	Yes	Yes	Yes	Yes
Isolation
Overvoltage category	II	II	II	II
EMC
Compliance with line harmonic distortion limits
● Compliance with line harmonic distortion acc. to IEC 61000-3-2, IEC 61000-3-3	Yes	Yes	Yes	Yes
Degree and class of protection
Equipment protection class	I, with protective conductor	I, with protective conductor	I, with protective conductor	I, with protective conductor
Standards, approvals, certificates
FM approval	Yes; Ta: 0 °C to 70 °C T4	Yes; Ta: 0 °C to 70 °C T4	Yes; Ta: 0 °C to 70 °C T4	Yes; Ta: 0 °C to 70 °C T4
Ambient conditions
Ambient temperature during operation
● min.	0 °C	0 °C	0 °C	0 °C
● max.	60 °C	60 °C	60 °C	60 °C
connection method / header
Design of electrical connection	3x 1.5 mm², solid or stranded wire with end sleeve, external diameter 3 mm to 9 mm	3x 1.5 mm², solid or stranded wire with end sleeve, external diameter 3 mm to 9 mm	3x 1.5 mm², solid or stranded wire with end sleeve, external diameter 3 mm to 9 mm	3x 1.5 mm², solid or stranded wire with end sleeve, external diameter 3 mm to 9 mm
Dimensions
Width	25 mm	50 mm	50 mm	50 mm
Height	290 mm	290 mm	290 mm	290 mm
Depth	217 mm	217 mm	217 mm	217 mm
Weights
Weight, approx.	760 g	1 200 g	1 200 g	1 300 g