Sct Current Sensor Problem
Sct Current Sensor Problem Video
A 100A sensor is rather large for reading 0.09 Amps. If somehow, you read 100A with an analog input the resolution is 100/1024, or about 0.1 Amp. So your no current signal is down in the noise or possible magnetising current errors.
YHDC SCT-013-000 Current TransformerA Report on the properties of the YHDC current transformer and its suitability for use with the OpenEnergyMonitor system.by Robert Wall B.Sc., C.Eng., MIEE.Datasheet: SynopsisThe Yhdc current transformer is manufactured by Beijing YaoHuadechang Electronic Co., Ltd and is widely available from many stockists as Non-invasive AC current sensor (100A max), Model SCT-013-000.It has no internal burden resistor, but a transient voltage suppressor limits the output voltage in the event of accidental disconnection from the burden. It is capable of developing sufficient voltage to fully drive a 5 V input. For test currents up to 100 A, the CT primary consists of from 1 to 20 turns of insulated 16/0.2mm wire. The majority of tests were made at 5 A – thus the primary current seen by the CT could be adjusted in steps of 5 A by enclosing a variable number of turns inside the core. For saturation tests up to 250 A, the primary consists of 50 passes of enamelled copper wire, the current being adjusted in this case.(Note: The current exceeds the rating of the wire used for the primary, but as the coil is loosely bunched except where it passes through the transformer core, and because each test is of relatively short duration, heating is not a problem).The primary current was monitored by the 0.33Ω shunt.
The potentiometers, current limiting resistor and diodes, in both the shunt and the CT outputs, are to protect the computer sound card from over-voltage and switching transients. Primary CurrentSecondary CurrentDesign Secondary Currenterror0.50.25340.251.50.80%1.50.750.750.1.20%52.452.5-2.00%105.071.251.312.352.63.563.634.6940.7250.268.770-1.86%801.9100.5The measured ratio is comfortably within the specification ( ± 3% over the range 10 A to 120 A).The error becomes meaningless above about 140 A as saturation sets in. In this area, the waveform becomes increasingly distorted and unusable for measurement purposes.The test was repeated with a 22 Ω resistor as the burden, and this time measuring the burden voltage. Currents up to 250 A were applied in order to observe the effect of core saturation.The saturation curve (showing rms current or voltage) fails to reveal the true situation because in any case, the peak-peak burden voltage – which in saturation is no longer directly related to the rms voltage – exceeds the emonTx & emonPi input range at a little over 100 A, and currents above this maximum value risk damaging the ADC input.2.
Sct Current Sensor Problem Chart
Phase error.The phase error was measured for 3 values of burden resistor.
From the website the SCT-013-050 outputs 0 to 1 volt for a current of 0 to 50 amps.I agree the 'burden' resistor is built in on this module.Please verify you are only passing one of the coffeemaker wires through the sensor. If you pass the whole cable through the sensor you will get no output voltage from the sensor.A typical coffee maker requires 1000 watts.
At 230 vac this is 4 amps. So the output of the current sensor should be about +/- 4/50.1 = 0.08 volts. This means the arduino has to measure readings from 0 to about 0.11 volts then calculate the RMS.
Doable but the readings are getting somewhat small to be stable.I would suggest:.measure the sensor output with a multimeter if you have one.Change the reference of A/D converter on the Arduino from the default to the 1.1V internal reference. Not sure the code but you should be able to find it easy enough.you can increase the output of the sensor by passing the coffee maker wire through multiple times. Savage xr for windows 8. For each time the wire goes through the sensor the sensitivity is increased by that number.for example if you pass the wire through the sensor 3 times.
The output becomes 0 to 1 volt for 0 to 50/3 amps.Add a 0.1µF Capacitor across the sensor (where the burden resistor is shown on your diagram. This will remove some of the noise that exists on all AC lines.