AC Withstand Hipot Test

[Nick_Krazy8]

I’m trying to provide a safe procedure to perform an ac withstand hipot test (60 sec) in a crane car used in the railway industry. Test voltage will be around 1.24 to 2.4 KV depending on the circuits. No experience in the testing field and I want to consider all safety concerns. Anybody can guide me through this?

 

[ATSman]

You did not specify if this was new equipment (Acceptance Tests) or already in service (Maintenance Tests.)
Attached are the NETA MTS (2011) and ATS (2009) Tests specs that we use. Or you can obtain the latest versions.
If you plan to do the tests yourself you will have to go thru the hassle of renting the equipment, learning how to use it, and accepting the liability of providing the results. And also the responsibility if somebody gets hurt during the testing as these are lethal test voltages. If this sounds uncomfortable then hire a NETA certified testing firm to perform the work and avoid all the trouble and liability. Good luck!
BTW I think NETA is international (INETA) so they should be recognized in Canada but verify that first.

 

[paulengr]

I’m trying to provide a safe procedure to perform an ac withstand hipot test (60 sec) in a crane car used in the railway industry. Test voltage will be around 1.24 to 2.4 KV depending on the circuits. No experience in the testing field and I want to consider all safety concerns. Anybody can guide me through this?

How about this? IEEE 400 is the standard for hipot and it says don’t do it!!

Putting Hipot Out to Pasture

As DC high-potential testing starts to show its age, test methods recommended by IEEE are ready to fill the void For many years, high-voltage DC testing has been the traditionally...

www.ecmweb.com

Hipot testing does not show anything useful and it can induce failures that “pass” the test then show up later.

Safety wise any “high voltage” test is the same. You isolate the wiring, ground everything but the equipment under test, run the test, then ground out the equipment under test for a minimum of 3 times the testing time. Usually just use caution tape. The current in hipot does not exceed 1 mA so an accidental shock will startle you and it hurts but it is definitely not fatal. Voltage does not matter when it comes to shocks…it’s current. A hipot can certainly put out more current than a Megger test but both are no worse than touching an electric livestock fence or a spark plug. So it falls under “warning”, not “danger”. I test motors of all sizes, especially large ones all the time. Once in a while my crew messes up and we’ve accidentally zapped each other in testing when we aren’t coordinating well with each other.

 

[kwired]

How about this? IEEE 400 is the standard for hipot and it says don’t do it!!

Putting Hipot Out to Pasture

As DC high-potential testing starts to show its age, test methods recommended by IEEE are ready to fill the void For many years, high-voltage DC testing has been the traditionally...

www.ecmweb.com

Hipot testing does not show anything useful and it can induce failures that “pass” the test then show up later.

Safety wise any “high voltage” test is the same. You isolate the wiring, ground everything but the equipment under test, run the test, then ground out the equipment under test for a minimum of 3 times the testing time. Usually just use caution tape. The current in hipot does not exceed 1 mA so an accidental shock will startle you and it hurts but it is definitely not fatal. Voltage does not matter when it comes to shocks…it’s current. A hipot can certainly put out more current than a Megger test but both are no worse than touching an electric livestock fence or a spark plug. So it falls under “warning”, not “danger”. I test motors of all sizes, especially large ones all the time. Once in a while my crew messes up and we’ve accidentally zapped each other in testing when we aren’t coordinating well with each other.

FWIW I have been "knocked out" by livestock electric fence before. Some them run 15kV +

 

[Nick_Krazy8]

You did not specify if this was new equipment (Acceptance Tests) or already in service (Maintenance Tests.)
Attached are the NETA MTS (2011) and ATS (2009) Tests specs that we use. Or you can obtain the latest versions.
If you plan to do the tests yourself you will have to go thru the hassle of renting the equipment, learning how to use it, and accepting the liability of providing the results. And also the responsibility if somebody gets hurt during the testing as these are lethal test voltages. If this sounds uncomfortable then hire a NETA certified testing firm to perform the work and avoid all the trouble and liability. Good luck!
BTW I think NETA is international (INETA) so they should be recognized in Canada but verify that first.

Thanks, ATSman for all the advice! The test is an acceptance test since it's for a new project in a manufacturing environment. But I am not sure if NETA ATS works for us. The client says "all circuits and connected apparatus shall be subjected to dielectric tests in accordance with the latest IEEE standards. All circuits shall withstand a potential of twice the rated voltage of the conductor or connected equipment whichever is less, plus 1000 VAC, applied continuously for 60 sec between ground and current-carrying parts. The equipment and apparatus shall be disconnected before the test." I have difficulties interpreting this. Questions are 1) Do I need to test all control wires or only power wires tests with Hipot? 2) What about the wires already connected to a Terminal Block using a ferrule or wires already connected using a ring terminal, lug, or even a pin or socket? 2) Client used "Circuit" versus "Wire". Does it mean all wires in one circuit have to be tested altogether? 3) Any suggestion on which IEEE standard might work for our application: We have 600V and 2000V rated wires and cables, and 24VDC and 96VDC are two levels of the voltage we have in the machine. I will consider your advice regarding NETA certified technician, but for now, I need to understand what we have to implement. Thanks in advance!

 

[Nick_Krazy8]

How about this? IEEE 400 is the standard for hipot and it says don’t do it!!

Putting Hipot Out to Pasture

As DC high-potential testing starts to show its age, test methods recommended by IEEE are ready to fill the void For many years, high-voltage DC testing has been the traditionally...

www.ecmweb.com

Hipot testing does not show anything useful and it can induce failures that “pass” the test then show up later.

Safety wise any “high voltage” test is the same. You isolate the wiring, ground everything but the equipment under test, run the test, then ground out the equipment under test for a minimum of 3 times the testing time. Usually just use caution tape. The current in hipot does not exceed 1 mA so an accidental shock will startle you and it hurts but it is definitely not fatal. Voltage does not matter when it comes to shocks…it’s current. A hipot can certainly put out more current than a Megger test but both are no worse than touching an electric livestock fence or a spark plug. So it falls under “warning”, not “danger”. I test motors of all sizes, especially large ones all the time. Once in a while my crew messes up and we’ve accidentally zapped each other in testing when we aren’t coordinating well with each other.

Thanks, Paulengr! I am not sure if IEEE 400 works, since the system is less than 5KV. I don't have access to the standard but the internet says it's for above 5KV. Our system use 600V and 2000V rated wires, 1000V- 2000V rated contacts (Pins, ferrules, ring terminals), and 24VDC and 96VDC as the main power source. Wondering if any other IEEE standard might work or IEEE 400 is the one that I need?
Here is what the client asked: "all circuits and connected apparatus shall be subjected to dielectric tests in accordance with the latest IEEE standards. All circuits shall withstand a potential of twice the rated voltage of the conductor or connected equipment whichever is less, plus 1000 VAC, applied continuously for 60 sec between ground and current-carrying parts. The equipment and apparatus shall be disconnected before the test." I have difficulties interpreting this. Questions are 1) Do I need to test all control wires or only power wires tests with Hipot? 2) What about the wires already connected to a Terminal Block using a ferrule or wires already connected using a ring terminal, lug, or even a pin or socket? 2) Client used "Circuit" versus "Wire". Does it mean all wires in one circuit have to be tested altogether?