Hey everyone!
I want to measure Appearant Power (S), Real Power (P), and Reactive Power (Q).
My load is Heat Pump Water Heater (HPWT) with input voltage of 240V.
Currently I have voltage and current transducer implemented in my circuit.

The output singals of both transducers are DC, so what are the possible ways to measure the phase angle and power factor besides the S, P, and Q?

Thanks,

 

You need a transducer that shows the current phase-angle, and a transducer the shows the voltage phase-angle
Voltage and current transducers normally do that so why do you have transducers that have a DC output if you wanted to measure real power?

 

What are your transducers?
You would be better off with simple voltage and current transformers.
Sample at >1kHz. Take a RMS average of V and I separately to give voltage and current. Multiply the averaged voltage value with the averaged current value to give VA.
Multiply the voltage sample with the current sample then average (simple mean, not RMS) to give the real power.
Power factor is P/VA.

 

With DC output transducers your options are rather limited, unless you can also get a phase angle output. Otherwise all you can get is volts, amps, and watts.
What information do you have about the transducer that you have installed. It might have what you need, no telling.

 

Hi everyone!
I'm using ZMPT101B and HSTS016L voltage and current transformers to measure S,P,Q,PF and phase angle.
My DAQ is a Rpi with MCP3008 in python environment. While running a test to collect data over 4 hours, voltage value is almout around 119V while the current is constant all the time which is not expected because my load is a heat pump water heater. Anyone has a thought or can help to solve this issue?
the input voltage is 120VAC, 60 Hz

 

What is the input voltage range of your DAQ? (Presumably 0-3.3V or 0-5V)
What circuitry are you using to interface the ZMPT101B and HSTS016L to the DAQ?
How are you processing the acquired data?
Do you really need phase angle? It's hard to deal with if the waveform is not a sinusoid.
Have you changed your mind about transducers since this post?
https://forum.allaboutcircuits.com/...re-power-and-phase-angle.202125/#post-1926230

 

Post #3 in your previous thread answered your question.
Why are you asking it again?

 

You need a transducer that shows the current phase-angle, and a transducer the shows the voltage phase-angle
Voltage and current transducers normally do that so why do you have transducers that have a DC output if you wanted to measure real power?

I'm using a VAC500-42L voltage transducer and CCT40-102 current transducer, they both generate DC signal as an output.

 

With DC output transducers your options are rather limited, unless you can also get a phase angle output. Otherwise all you can get is volts, amps, and watts.
What information do you have about the transducer that you have installed. It might have what you need, no telling.

Yes, this is what I'm struggling with. I need to measure the power factor so I need the phase angles.
I'm using VAC500-42L voltage transducer and CCT40-102 current transducer

 

What are your transducers?
You would be better off with simple voltage and current transformers.
Sample at >1kHz. Take a RMS average of V and I separately to give voltage and current. Multiply the averaged voltage value with the averaged current value to give VA.
Multiply the voltage sample with the current sample then average (simple mean, not RMS) to give the real power.
Power factor is P/VA.

I see. This made it even easier.
S = V-rms * I-rms
P = mean (V * I)
Then PF = P/S

Is that correct?

 

Yes, this is what I'm struggling with. I need to measure the power factor so I need the phase angles.
I'm using VAC500-42L voltage transducer and CCT40-102 current transducer

All you can get from that setup is Volts, Amps And VA. (Not Watts, nor power factor, nor phaseangle)

 

I see. This made it even easier.
S = V-rms * I-rms
P = mean (V * I)
Then PF = P/S

Is that correct?

Yes.

 

What is the input voltage range of your DAQ? (Presumably 0-3.3V or 0-5V)
What circuitry are you using to interface the ZMPT101B and HSTS016L to the DAQ?
How are you processing the acquired data?
Do you really need phase angle? It's hard to deal with if the waveform is not a sinusoid.
Have you changed your mind about transducers since this post?
https://forum.allaboutcircuits.com/...re-power-and-phase-angle.202125/#post-1926230

Yes I changed my mind about the transducers since they provide only DC signals as an output.

Now, I'm using the ZMPT101B and HSTS016L with Rpi and ADC MCP3008 chip. (Python environment)
Vcc for the voltage sensor is 3.3V and current sensor is 5.0V
I don't really need the phase angle but I need the power factor.

The voltage sensor is working as expected but I'm struggling with current sensor since it giving me a contant reading which is not corrent with my load.
I measured the output voltage of the sensor using a multimeter and it is always 2.5V, with/without current flowing.
Based on the datasheed it should be 2.5 VDC when no current is flowing. and with current flowing it should be 2.5 ±0.625 V.
Assuming that the issue but don't know how to solve it.

 

Yes, this is what I'm struggling with. I need to measure the power factor so I need the phase angles.
I'm using VAC500-42L voltage transducer and CCT40-102 current transducer

Yes I changed my mind about the transducers since they provide only DC signals as an output.

Now, I'm using the ZMPT101B and HSTS016L with Rpi and ADC MCP3008 chip. (Python environment)
Vcc for the voltage sensor is 3.3V and current sensor is 5.0V
I don't really need the phase angle but I need the power factor.

The voltage sensor is working as expected but I'm struggling with current sensor since it giving me a contant reading which is not corrent with my load.
I measured the output voltage of the sensor using a multimeter and it is always 2.5V, with/without current flowing.
Based on the datasheed it should be 2.5 VDC when no current is flowing. and with current flowing it should be 2.5 ±0.625 V.
Assuming that the issue but don't know how to solve it.

What circuitry are you using to interface the ZMPT101B and HSTS016L to the DAQ?

 

What circuitry are you using to interface the ZMPT101B and HSTS016L to the DAQ?

For the VT, the input voltage is 120V from the wall outlet that is feeding the heat pump, taking one phase only. The output pins of the VT, Vcc connected to 3.3 V of the pi, V0 is grounded, and Vout is connected to the ADC MCP3008.
The CT is clamped to the line that is feeding the load and the wires Vcc connected to 5V of the pi, Ground is grounded and Vout is connected to the ADC.

 

What values of burden resistor are you using?
How much current are you running through the ZMPT101B.
Did you bias the outputs at half supply?

 

I don't really need the phase angle but I need the power factor.

Save train of samples from two channels of DAQ or oscilloscope for 2-3 periods of signal.
One channel for voltage, other for current.
Type of file should be .xls or .csv or .txt.
Then you can calculate in Excel phase shift and power factor.

 

Welcome to AAC.

Is this a homework/coursework problem?

 

Yes I changed my mind about the transducers since they provide only DC signals as an output.

Now, I'm using the ZMPT101B and HSTS016L with Rpi and ADC MCP3008 chip. (Python environment)
Vcc for the voltage sensor is 3.3V and current sensor is 5.0V
I don't really need the phase angle but I need the power factor.

The voltage sensor is working as expected but I'm struggling with current sensor since it giving me a contant reading which is not corrent with my load.
I measured the output voltage of the sensor using a multimeter and it is always 2.5V, with/without current flowing.
Based on the datasheed it should be 2.5 VDC when no current is flowing. and with current flowing it should be 2.5 ±0.625 V.
Assuming that the issue but don't know how to solve it.

I am guessing that the current sensor is a positive output only device and that instantanious current results in variations above and below that 2.5 volt output offset. Those variations will not show on an average reading meter. So you need a much faster display, such as an oscilloscope, or a very fast A/D converter, with one millisecond or less updates.

 

I am guessing that the current sensor is a positive output only device and that instantanious current results in variations above and below that 2.5 volt output offset. Those variations will not show on an average reading meter. So you need a much faster display, such as an oscilloscope, or a very fast A/D converter, with one millisecond or less updates.

ZMPT101B is a 2mA:2mA current transformer. It Is driven from the mains with a resistor to limit the current to 1mA, and the output needs a burden resistor or a trans impedance amplifier.
The other device is a split -core current transformer (also needs a burden resistor or a trans impedance amplifier)
Both Need the output biassing to half supply.