Efficient AC Hipot Testing on Bucket Trucks
- Question 1: How often do I need to test my Bucket Trucks?
- Everyone company has its own guidelines, but ANSI A92.2 says at minimum every three years. Many Utilities test their trucks every four to six months depending on use and environment.
- Question 2: Should I test my Bucket Truck with AC or DC?
- ANSI A92.2 allows for both AC and DC testing, but most companies prefer AC testing because AC powerlines are more common.
- Question 3: Do all Bucket Trucks require the same testing?
- No, there are many types of Bucket Trucks. Category A, B and C trucks require testing at different voltages.
- Question 4: Do I need to save my Bucket Truck test results?
- Yes, written data and signed results should be retained for five years. The HAEFELY HIPOTRONICS’ HVT-DI AC Hipot can digitally save test results and export to external storage such as a USB Drive.
Power Frequency Magnetic Field Testing
- Question 1: What standards do I use for Magnetic Field Testing?
- IEC 61000-4-8 and IEC 61000-4-9 are international standards used for testing equipment immunity when subjected to a magnetic field. IEC 61000-4-8 specifically is for magnetic fields generated by power frequency current in a nearby conductor or other devices.
- Question 2: What magnetic field levels do I need to test my equipment up to?
- IEC 61000-4-8 specifies Levels 1-5 for continuous field strength ranging from 1-100A/m with 30A/m being the most common. Short duration testing (1-3s) is less common but has a higher field strength equal to 10x the continuous field. Starting with Level 4, (Levels 1-3 are not applicable) short duration testing ranges from 300-1000A/m. The HAEFELY HIPOTRONICS MAG 1000 is an inexpensive plug and play unit that allows testing for both continuous and short duration testing without the necessary for a secondary power supply or control unit.
- Question 3: How do I test larger devices that don’t fit within the standard magnetic field coil?
- Use the proximity method instead of the immersion method. With proximity testing, the inductive coil is moved along the side of the EUT in order to detect particularly sensitive areas. Results may not be as reproducible but this is a more favorable approach when compared to creating larger custom coils to attempt the immersion method.
Portable and Efficient: An Optimized Way to Measure Winding Resistance on Power Transformers
There are major challenges to gaining fast, efficient, and accurate measurement of winding resistances on large power transformers. Scalability and efficiency for this task have long seemed to be a pipe dream.
Some of the challenges include:
- Long charging and discharging times
- Inaccurate temperature measurements for resistance correction
- Residual magnetism and its unwanted effects
- Inefficient connection and disconnection of measuring equipment