Dynacord H 5000, H 2500 owner manual Power-On Delay and Softstart, Output Short Circuit Detection

PowerH SERIES

The power amp’s CPU is acquainted with the temporal progression of the mains current consumption and therefore can simulate the typical behavior of a mains circuit breaker. Nevertheless, pulse peaks allow crest currents that can exceed the nominal value by a multiple. RMS measurement of the mains current consumption allows the CPU to emulate the temperature curve of a circuit breaker’s thermal trip, which in return enables the Mains Circuit Breaker Protection to let the power amplifier work till shortly below the trigger level of the automatic circuit breaker. With typical concepts, especially for those without RMS current measurement, output power reduction has to be applied much earlier. During the processing of musical program material, the Mains Circuit Breaker Protection normally does not have to reduce the power amp’s output power. At most, with settings that are noticeably below the pre-set values of 16 A or 30 A respectively, (which may be reasonable when operating multiple power amps via a single automatic circuit breaker) output power reduction might become necessary to prevent the mains fuse from blowing.

Power-On Delay and Softstart

A Power-On Delay of up to 6.35 seconds can be programmed for the power amp via the LC display. Upon pressing the mains switch the power amplifier does not start until the set delay time has elapsed. If several power amps are operated on the same automatic circuit breaker, cascaded switch-on can be accomplish by programming individually different power-on delays for the amps. This also prevents the magnetic trip of an automatic circuit breaker from acting and thus disconnecting the power amplifiers from the mains supply, when various amps are switched on at the same time. The internal soft-start function additionally suppresses current peaks during power-on, which ensures trouble-free operation of PowerH SERIES amplifiers even on very sensitive automatic circuit breakers.

Output Short Circuit Detection

The corresponding output voltage and output current is measured for both output channels as soon as the power amplifier processes an audio signal. These readings are used to monitor the connected loudspeaker loads. The power amplifier has the ability to continuously deliver very high output currents. For example, if, in spite of a low output voltage, the current flow is high as the consequence of a short- circuit in one of the speaker lines, the power amp detects this fault condition and immediately disables signal output to protect connectors and cables against damage from overload. This, of course, also protects the power amplifier itself from being damaged by excessive electrical or thermal overload.

Advanced Thermal Protection

The PowerH SERIES amplifiers are the first to feature the new Advanced Thermal Protection (ATP). This new system differs in a trend-setting manner from traditional thermal protection measures, which, as soon as the fans are not any longer capable of dissipating the lost heat, mostly switch off the entire signal path at a relative early stage. With the ATP system switching off the signal path is last of three consecutive measures. Prior to making this final step, the system uses two other approaches to limit the amp’s power, so that it returns to a thermally stable operational range.

The first step is Voltage Limitation. This measure reduces the internal supply voltage of the power amplifier blocks, which, objectively, is at the expense of reducing the voltage dynamic. During the reproduction of music or speech, however, this effect is subjectively hardly perceived. Despite the negligible acoustic influence, the efficiency gained in the power amp is so high that the development of heat is clearly

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