Stargazer
Surin Legend
Arriving back in Thailand, my grandpa job is 'Mr. Fixit'. Amazing how many things can break in 6 months! I do have pretty good troubleshooting experience. My successful isolation of problem may help someone else.
One of the two well pumps, ½ hp about 40 meters down, had stopped working. (Franklin pumps) Power OK, pump controller OK, just kept tripping breaker. Two possibilities left: pump wiring connections at pump failed, allowing short. Or pump motor seal failed, flooding motor, allowing short. Ugh. Time to pull the pump, not fun.
Wait! I examine main breaker for rice field buildings. It has a little RSQP switch about the size of a pencil lead. I remembered that we had some problems at our house with a safety breaker always tripping on the pump line. So I tried turning off RSQP. Pump then worked fine, nothing wrong.
Analysis: (I am not an electrical engineer, but was a licensed electrical contractor as part of design/building homes in California) It is my understanding that sensitive ground fault breakers can be activated by either too many connected devices that shunt power surge peaks to ground (which, added up, look like a ground fault), or by long wire runs with inductive losses, or connected induction motors. My theory is that typical pump installations in Thailand can create the latter condition.
In the case of our home, the solution that worked was to bypass the whole house safety breaker just for the pump circuit, and connect the pump top metal connector to ground stake. One way to test if there is significant leakage current is to measure from top of well to ground.
As there are some safety risks involved here, I do not recommend following my solution without professional help. But it works for us. I have no idea what PEA's position is about this issue, and I prefer to not involve them lest it get bureaucratic. Certainly, you do want most house circuits protected by RSQP, which in Thailand works a bit differently than in USA, as it simply measures the current going out the hot and compares to that returning on the neutral. If there is a difference above a certain (sometimes adjustable) threshold, it reasons that there is a ground fault, and trips off.
One of the two well pumps, ½ hp about 40 meters down, had stopped working. (Franklin pumps) Power OK, pump controller OK, just kept tripping breaker. Two possibilities left: pump wiring connections at pump failed, allowing short. Or pump motor seal failed, flooding motor, allowing short. Ugh. Time to pull the pump, not fun.
Wait! I examine main breaker for rice field buildings. It has a little RSQP switch about the size of a pencil lead. I remembered that we had some problems at our house with a safety breaker always tripping on the pump line. So I tried turning off RSQP. Pump then worked fine, nothing wrong.
Analysis: (I am not an electrical engineer, but was a licensed electrical contractor as part of design/building homes in California) It is my understanding that sensitive ground fault breakers can be activated by either too many connected devices that shunt power surge peaks to ground (which, added up, look like a ground fault), or by long wire runs with inductive losses, or connected induction motors. My theory is that typical pump installations in Thailand can create the latter condition.
In the case of our home, the solution that worked was to bypass the whole house safety breaker just for the pump circuit, and connect the pump top metal connector to ground stake. One way to test if there is significant leakage current is to measure from top of well to ground.
As there are some safety risks involved here, I do not recommend following my solution without professional help. But it works for us. I have no idea what PEA's position is about this issue, and I prefer to not involve them lest it get bureaucratic. Certainly, you do want most house circuits protected by RSQP, which in Thailand works a bit differently than in USA, as it simply measures the current going out the hot and compares to that returning on the neutral. If there is a difference above a certain (sometimes adjustable) threshold, it reasons that there is a ground fault, and trips off.