Ripple

Unregulated direct current supplies:

The ripple (Ref.: DIN 41 755-1) is the ratio of the effective value of the superimposed alternating voltage Us to the value of the arithmetical direct current voltage Ud and is specified in percentage form:

*eff only ac
**arithm.

The test setup is identical for single-phase
and 3-phase direct current supplies:

P = direct current power supply
S = mains
B = Rated
V = User

Unless otherwise specified, the specification of the ripple refers to the load with rated direct current and an actual load impedance.

Regulated direct current supplies:

In contrast to unregulated direct current supplies with ripples in the volt range, regulated direct current supplies possess only very low levels of ripple. For that reason, this is no longer given as a percentile value but rather as an absolute voltage value in mVss (millivolt peak-peak), it is furthermore maximally independent of the level of the output direct current in the assigned functional area. Non-sinusoidal ripples (e.g. spikes) which exhibit wide-band frequency behaviour can occur as the result of regulating and switching procedures within the regulated direct current supply.

Qualitative differences in the ripple of the output direct current voltage also exist between the linearly-regulated and the clock-pulse controlled direct current supplies.

If the important thing is a supply direct current voltage which is as “clean” as possible, as is the case for example in measurement and regulation technology, then one should regard linearly-regulated direct current supply as the preferable alternative.