I am facing the CE failure issue in one of my design.
Major components: SCR, MOSFET, Controller.
Project: Timer based product.
Working: Initially the SCR in OFF condition for 1 milli second means controller gives the high signal to the base of NPN when the set timing has been complete from the controller afterwards SCR has been ON and will be on condition(for rest of 9 milli second) until zero crossing detect.
By turning ON/ OFF the SCR resulting to create the unwanted harmonics causing it failing in the CE test.
CE test results attached and schematics attached below.
SCR part number: TS420-600
MOSFET part number: 4NK80ZT4 DPAK

 

I am facing the CE failure issue in one of my design.
Major components: SCR, MOSFET, Controller.
Project: Timer based product.
Working: Initially the SCR in OFF condition for 1 milli second means controller gives the high signal to the base of NPN when the set timing has been complete from the controller afterwards SCR has been ON and will be on condition(for rest of 9 milli second) until zero crossing detect.
By turning ON/ OFF the SCR resulting to create the unwanted harmonics causing it failing in the CE test.
CE test results attached and schematics attached below.
SCR part number: TS420-600
MOSFET part number: 4NK80ZT4 DPAK

View attachment 328584
View attachment 328585

Hi guys
Could you please help me in the above mentioned Issue.

 

Your spectrum overview is a bit confusing and difficult to read. I presume your QP is the blue graph which gives you 2 incursion points below 200kHz, and the red is your Peak Positive?
I have no idea of the current consumption of your device but I would suggest you use a common mode choke on your mains input lines to remove most of the low-frequency noise. The choke should be rated appropriately for the current consumption.
Common mode chokes are more effective than a simple LC low pass filter.

 

Your spectrum overview is a bit confusing and difficult to read. I presume your QP is the blue graph which gives you 2 incursion points below 200kHz, and the red is your Peak Positive?
I have no idea of the current consumption of your device but I would suggest you use a common mode choke on your mains input lines to remove most of the low-frequency noise. The choke should be rated appropriately for the current consumption.
Common mode chokes are more effective than a simple LC low pass filter.

The device's current consumption is 700mA due to the use of the SCR.

At this stage of testing, we are unable to modify the design or make any changes to the PCB. If you have any better options or suggestions, please let us know.

 

At this stage of testing, we are unable to modify the design or make any changes to the PCB.

That's going to make life difficult.

What exactly does the device do?
Does it pass the harmonic current regulations?

 

Your spectrum overview is a bit confusing and difficult to read. I presume your QP is the blue graph which gives you 2 incursion points below 200kHz, and the red is your Peak Positive?
I have no idea of the current consumption of your device but I would suggest you use a common mode choke on your mains input lines to remove most of the low-frequency noise. The choke should be rated appropriately for the current consumption.
Common mode chokes are more effective than a simple LC low pass filter.

Quasi-peak is red, and the red limit line applies to quasi-peak.
Average is blue and the blue limit line applies.
Quasi-peak is always more than average.

 

@Ian0
I know, I can see a couple of clear peaks above the limit line between 150-200KHz, then one line at around 4 that I cant see where it ends and a couple around 16-18MHz and they are below the limit lines...

 

The circuit seems a strange design to achieve a low voltage from the rectified mains.

If the circuit is drawing 700mA from the 240V~ source, then resistor R1 is dissipating over 150W.