Electronic, electrical products’ intermittent conduction emission of exceeding standard problems, and the countermeasures.
The intermittent conduction harassment nominal measuring frequency range of home appliance products is 148.5 kHz-30MHz (The actual is 150 KHZ – 30 MHZ).
The measurement was done on power terminal, and the click measurement frequency point is: 150kHz、500kHz、1.4MHz、30MHz.
The main source of intermittent conduction harassment:
Thermostatically controlled appliances, machines with automatic program, and other switch operations of electrical controlling or operating appliances will produce the intermittent disturbance; this kind of operation can be achieved through the relay and SPC electronic/mechanical switch.
Such harassment is generally formed by contact jitter of relay switch, and the surge impact of non-pure resistance load on and off, in view of the above two aspects, we can take the corresponding disturbance suppression measures.
Electronic electrical products radiation harassment of exceeding-standards and the countermeasures.
The measurement frequency range of radiation disturbance field strength of electronic electrical products is 30MHz-1000MHz, the measurement is generally carried out in the open field or half-wave dark room.
The main disturbance source of radiation harassment:
The switch frequency of switch power supply and harmonic disturbance
AC motor operation noise and DC motor brush noise
The electromagnetic disturbance of electromagnetic induction equipments
The crystal oscillator of Intelligent control equipment and digital circuit electromagnetic disturbance etc.
When we find the harassment source of the radiation harassment point of exceeding-standard through locating the harassment position, then we can take the corresponding disturbance source control measures. (The introduction is made respectively according to the fault location and disturbance sources).
Generally speaking, firstly the disturbance source has to be suppressed; this can be achieved through optimizing circuit design, circuit structure and typesetting, strengthening filtering and correct grounding. Secondly, the coupling paths should be cut off, this can be achieved through the correct casing shielding and transmission line filtering.