Start a new topic

AC TEST, PILOT and GFCI questions

Hi!, I thank a lot for your answers on these simple questions:
from the website:

"AC Test

The two AC line monitor chips act as opto-isloators. The presence of an AC voltage potential relative to ground on either L1 or L2 will result in a state change from High to Low appearing on PD3 and PD4 of the CPU. Since the test pins are downstream of the relay, there should be no voltage present (pin state HIGH) the relay is open. This is how the stuck-relay test is accomplished. Automatic selection between L1 and L2 is accomplished by observing the state while the relay is closed. L1 will have a LOW state on only one line, L2 will have LOW state on both. A lack of voltage preasent on both while the relay is closed is a ground test failure."

1. Can you please explain the last sentence? What is a lack of voltage? What value do you mean? 
2. If the EVSE is connected to 110VAC then one line is Neutral and the other is Line(hot), this means that only Line(hot) will trigger the optocoupler, correct?
What is the expected voltage between Neutral and GND? sometimes it may higher than 40V or more. Would that trigger the optocoupler? What would the CPU do?
3. For Level 2 that uses 220Vac, what are the expected voltages between line1, line2, earth and GND?
4. How do you define and detect ground fault? I did not understand the description.

5. Isn't the TVS diode preventing the PILOT signal from ever getting to -12V? It is connected between PILOT and GND, therefore -12V from the OPAMP would be limited to 0V.
6. Why are you using 620ohm on R1? why not standard 1k?
7. How do you do the ADC reading of the PILOTREAD pin if the signal is a PWM?

8. How many windings are you using in this transducer? You mention this is a custom part, can you share the specs?

9.What does IC5 do? (v5.5)

1 Comment

1. 0 volts

2. Neutral and ground should be 0v. The Opto would not likely be triggerd by 40v. If you had a false detect and you are using Service Level Auto, Level 1 would be falsly detected as Level 2. If you have Service Level set to L1 or L2 it would not matter at all.

3. Level 2 split Phase in North America, The both channels would detect, Auto Service level can be used. Voltages would be 120 - 120 and 0

For single phase just 1 chip would detect, Auto service level should be disabled. Voltages would be 230 - 0 and 0.

4. A ground fault is an inbalance of 15 - 20ma going in vs going out.

5. it is a bidirectional part that clamps at +16v or - 16v.

6. the OPAMP has internal resistance. Internal resistance + 620 = 1k total resistance lots of times.

8. whatever coil you choose with however windings it has will need to match a burden resistor on the controller to trip persisly at 15-20ma. The custom OpenEVSE part is a highly sensitive and precise coil with a nickel core. It trips GFCI at between 15 - 20ma. 

9. Drives contactors with an AC coil.

Login or Signup to post a comment