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Switch on an electrical device on which the standby symbol (IEC 60417-5009) can be seen. Although it is often referred to as the power button, it does not switch off the power supply, but only powers the device up / down.

The standby mode or standby mode (also wait mode ), the state of a technical device, in which the actual useful function is temporarily disabled, but can be reactivated at any time and without preparation or longer waiting times. To maintain the standby state, a specific power requirement that is reduced compared to normal operation is generally necessary. Examples of standby mode include consumer electronics devices such as televisions , DVD players, and personal computers . The apparent-off is also a state with a power requirement, but in contrast to the standby mode, it does not provide any useful function.

The Ecodesign Directive of the EU, which was adopted in 2008, came into force in 2010 and was tightened in 2014, limits the power requirement in pseudo-off and standby mode. Devices may not consume more than 0.5 watts when they are switched off  , and power supplies with an output of less than 50 watts even only 0.3 watts. When these devices perform additional functions in standby, e.g. B. display the time, then they may consume 1 watt.


In the field of entertainment electronics, operational readiness is often initiated by switching off a device using a remote control (standby or standby button). During the operational readiness, the device can be reactivated at any time by remote control without the need for direct intervention on the device, which is considered convenient. However, since it is necessary to leave at least the circuit for processing the remote control signals activated, the device continues to consume electrical energy in standby mode.

Only a small amount of power is required in standby mode compared to full use. The annual consumption of the standby can still exceed that of the company. For example, if a video recorder consumes around 25 W in operation  and is used 400 hours a year, this results in 10 kWh for operation  . If it only needs 4 W in standby mode, this power consumption adds up to around 35 kWh with 8760 standby hours per year.

In order to save energy, various devices have a function for automatic partial shutdown, for example a reduced brightness on LCD screens during longer periods of inactivity. The standby mode should not replace the complete switch-off, but rather help to reduce the power consumption of the devices in idle time.


In the case of computers, large parts of the internal electronics are switched off in standby mode, but they can be reactivated quickly so that you can continue working as soon as possible. For example, a reduction in the clock frequency or a so-called sleep mode for the processor and the disconnection of hard drives are common and are part of the standby mode .

This means that standby modes can be used to save energy by avoiding a time-consuming restart . However, the computer is not completely switched off and continues to consume electricity, typically 2% to 10% of normal consumption. This is why it is better to switch it off completely during longer breaks in use to save energy. In the case of personal computers , different standby modes or states are usually available with partial shutdowns of different extents or the down-regulation of different numbers of devices. The technical implementation usually takes place via the Advanced Configuration and Power Interface (ACPI), via which the standby modes "S1" to "S3" can be called.

With the so-called "suspend to RAM" (English, also "suspend to memory") the current system configuration is loaded into the main memory and most of the system components are switched off. Only the memory ( RAM ) is transmitted via the standby -Leitung of ATX - AC adapter still powered, otherwise the stored data would be lost. From the outside, the PC looks almost as if it were completely switched off, usually only one control lamp is switched on, which flashes slowly or changes color. As soon as the user uses an input device, for example the keyboard (in some cases the mouse is sufficient), the computer is switched back to operating mode and the user can continue working after a few seconds.

The idle state ("suspend to disk", ACPI state "S4"), in which the device no longer has to remain in operation, as the operating state is retained in non-volatile memories, is defined further as a standby mode . In this way, no energy is consumed in the idle state, whereby both the switching to the idle state ("falling asleep") and the reactivation ("waking up") take longer than in standby mode.

See also: Green IT

Power requirement


Commercially available electronic electricity meters are often imprecise with measured outputs of less than 2 W. Measurement errors over 10% are not uncommon. In addition, when measuring by the measuring device, only the portion of the real power and not the entire apparent power has to be recorded. In addition, effective values (RMS) must be measured, which is particularly important for consumers with a non-sinusoidal current curve and with different form factors .


Switchable socket strip

The power requirement can be reduced by circuit technology; standby powers in the double-digit milliwatt range are possible with power supplies with less than 5 W at moderate additional costs. As a rule, the user can disconnect the consumer from the mains voltage without using the standby power such as switching on using the remote control. This can be done using the primary-side power switch directly on the device, but there is the problem that it is not always clear to the user whether the power switch is attached to the primary side. Other simple methods include unplugging the device in question or using a switchable multiple socket outlet or a master-slave socket .

Remote-controlled sockets or timers also need electricity to operate, which only results in savings in exceptional cases.

Due to their function, a number of devices and facilities require an uninterrupted power supply and are normally in continuous standby mode. These include, for example, telephone systems , hazard alarm systems , measuring devices and telecontrol devices , but also mains-operated clocks.

Individual evidence

  1. Christof Windeck: One watt regulation., January 2009, accessed on May 19, 2014 .
  2. Guidelines accompanying Commission Regulation (EC) No 1275/2008. (PDF) EuP network, October 2009, accessed on March 21, 2014 (English).
  3. The RP-Energie-Lexikon: Standby losses at, last accessed in December 2014.
  4. Ernst Ahlers: current detectives in c't 21/2013 pp. 126-131; Article is also available online .
  5. Alexander Schink: Silent Stromfesser. In: c't . January 23, 2009. Retrieved January 16, 2017 .