Insulation resistance tester, commonly known as digital shaking table, digital megohmmeter, already more and more accepted by the general electric person.
A lot of the engineers of the old elevated from the shaking table, or rarely contact using shaking table recruits, are often used with the there is a lot of confusion.
Let's count one by one the soul torture:
Insulation resistance of the wire?
Measured power system must be first, will the insulation test voltage end of the insulation sheet and COM port, respectively connected to be measured.
With insulation wire measurement, for example, the end insulation rubber *, wire end, let tester - pens and - insulating rubber - wire - pens and - tester, into a loop.
[tips: * actual use pens and contact rubber insulation, suggest to use aluminum foil package such as insulating rubber, lest because pens and interface is too small, missed fault point]
Why the output voltage is always beating?
The basic principle of insulation resistance can be a typical analogy ohm's law: instrument have known resistance, constant output voltage, detecting current at the same time.To ensure personal safety and equipment safety, insulation table set limited current protection.If measured insulation resistance is low, breakdown, or local or distributed capacitance is bigger, current limiting protection function will work, at this time will be observed voltage fluctuations.Insulation table will be calculated according to the actual voltage and current, insulation resistance measurements are still can keep the accuracy.
[dry question 1: if the actual voltage, external insulation resistance value is too small. You should choose a lower output voltage, to correct the measurement.]
High pressure measuring safe?How to discharge instrument not grounded?
Fluke insulation table, all is the standard discharge circuit, through scientific design of the internal load, the end of the measurement of return to the instrument internal consume electricity.Ensure the safety of users.
The insulation of the three-phase motor test, and how the connection?
Instrument of two pens and or alligator clip, smokes measured motor winding, another version of the motor casing.
[dry torture] what chassis, which other one winding?
A: in fact, most of the time the two connection little influence on the measured data.
The insulation of the insulation table reading how have been?What reading is accurate?
Insulation table after pressing test, usually need to wait for 1 minutes reading, is the more accurate the insulation of the reading (actual conditions and the material being measured, temperature and humidity environment have relationship).
Because, after the tester to test dielectric charging into the state, the resulting current is insulation experience has three additional, thus affect the measured value, most of the additional current will be smaller with the passage of time.Specifically:
Capacitive current:
Effect of capacity, especially multilayer + the insulation of the different materials will be more apparent.The initial stage, to the 'capacitor charging, capacitance current is so large, as full charge, capacitive current gradually tends to zero.Lasts a few seconds to 10 seconds.[small] knowledge in insulation resistance is high, the motion of the test wire can also be showed obvious capacitor charging and discharging current
The absorption current:
Insulation material itself is molecular affected by testing electricity, rearrange absorbs absorbed electrical energy to generate electricity.Lasts 1 minute or more to tends to zero.
Leakage current:
More significant effect, much exists in the high insulation value + high test voltage (2500 v or above, for example), at 2500 v F1535 insulation table as an example, the 2500 v work, through the instrument attached G port to capture this part of the current, can make the test values more accurately.
Knowledge [small] so fluke 1508/1503 1000 v insulation table function is not configured leakage current.F1535 G port in 1000 v and below gear, generally do not need to use
Why test the same insulators, some table fluctuations is slow, also some table can quickly into stable readings and convenient judgment test values?
Answer: after understanding the second q, it is easy to answer: book one of the factors of the key is whether the maximum short-circuit current is large enough.Because resistance meter only can complete the uptake of capacitive current/faster after the power output of the current effect, to obtain the stable value.In addition of course, the whole circuit, transformer design and algorithm, integrated design, to ensure that the whole measurement process and the final result.
2500 v 500 g the hig雷竞技apph voltage insulation table Fluke 1535 -- commonly used in a wide range of 500 v 100 g Ω range, is 200 times that of the traditional insulation table 1000 v products.Mother don't have to worry about I saw [> 550 m Ω] outrange tips.
Product exclusive details page:http://www.雷竞技appfluke-ig.com/1535/
