Table of Contents
- 1 What is an acceptable ohm reading?
- 2 What is the minimum acceptable value of cable insulation resistance?
- 3 What is a bad reading on a Megger test?
- 4 How do you read insulation resistance?
- 5 How much resistance should a ground wire have?
- 6 Which is DC Hi Pot test for 5kv cable?
- 7 How many volts do you need to test a new cable?
- 8 Can a DC cable be tested for high potential?
What is an acceptable ohm reading?
If the megger reads a resistance under 1 (1,000 ohms) on your meter after the initial 60-second interval, the cable has failed and the cable should be removed. If the megger reads a resistance between 1-1.25 on your meter, then the cable passes. Any reading above 1.25 is considered excellent.
What is the minimum acceptable value of cable insulation resistance?
Insulation resistance should be approximately one megohm for each 1,000 volts of operating voltage, with a minimum value of one megohm.
What is the Megger value of cable?
1. IR Values For Electrical Apparatus & Systems
| Max.Voltage Rating Of Equipment | Megger Size | Min.IR Value |
|---|---|---|
| 600 Volts | 1,000 Volts | 100 MΩ |
| 5 KV | 2,500 Volts | 1,000 MΩ |
| 8 KV | 2,500 Volts | 2,000 MΩ |
| 15 KV | 2,500 Volts | 5,000 MΩ |
What is a bad reading on a Megger test?
What is a bad reading on a Megger test? If the megger reads a resistance under 1 (1,000 ohms) on your meter after the initial 60-second interval, the cable has failed and the cable should be removed. If the megger reads a resistance between 1-1.25 on your meter, then the cable passes.
How do you read insulation resistance?
Insulation resistance measurement is based on Ohm’s Law. (R=V/I). By injecting a known DC voltage lower than the voltage for dielectric testing and then measuring the current flowing, it is very simple to determine the value of the resistance.
What is the insulation resistance of a cable?
The insulation resistance is the resistance in ohms of wires, cables and electrical equipment. It is important to guard against electric shocks and avoid equipment damage from accidental discharges. The method of measuring the insulation resistance is to test and assess the state of the isolation (head and body.)
How much resistance should a ground wire have?
Ideally a ground should be of zero ohms resistance. There is not one standard ground resistance threshold that is recognized by all agencies. However, the NFPA and IEEE have recommended a ground resistance value of 5.0 ohms or less.
Which is DC Hi Pot test for 5kv cable?
This DC hi-pot testing applies to cable voltage rated 5kV and above. Refer to SAES-P-104 Para. 13.3, Table 3). Prior to DC hi-pot testing, perform cable continuity and phasing check for each cable. Check the insulation resistance of the cable using 5000 volts DC megger tester.
Can a 5kv Megger be used for high voltage test?
DC testing above 5kV of field aged XLPE cables generally increases water tree growth and reduces service life. 5kV is not considered a “High Voltage DC Test”. The test voltages for tests on XLPE cables is now limited to 5kV after in service repairs and 10kV for new installations. A 5kV Megger is suitable for a 5kV test on cables after repairs.
How many volts do you need to test a new cable?
In new cables, values of greater than 100 mega ohms are required. The integrity of the outer sheath shall be checked after cables have been buried by an insulation tester (Megger) at 1000 Volts. The test shall be conducted for 1 minute between each wire screen and earth after the cable has been jointed and terminations installed.
Can a DC cable be tested for high potential?
Such persons shall be capable of working safely and shall be knowledgeable on the precautionary techniques, personnel protective equipment, shielding and insulating materials and tools. High voltage cables shall be DC high-potential tested in accordance with SAES-P-104 Para. 13. This DC hi-pot testing applies to cable voltage rated 5kV and above.