MIT515, MIT525, MIT1025, and MIT1525 insulation resistance testers
Measures up to 30 TΩ
Insulation resistance up to 30 TΩ at 15 kV, 20 TΩ at 10 kV, and 10 TΩ at 5 kV
Safety rated up to CAT IV
Up to 1000 V to 3000 m for the MIT1525, and CAT IV 600 V to 3000 m for the MIT515, MIT525, and MIT1025
Additional protection with dual-case design
A tough outer case to protect the tester, an inner fire retardant case, and IP65 rated when closed
Full set of diagnostic test modes
Including Polarisation Index (PI), Dielectric Absorption Ratio (DAR), Dielectric Discharge (DD), step voltage (SV), and ramp test
New PI PredictorTM
Obtain 10 minute PI values in typically half the time with the new patented PI predictor.
À propos du produit
The MIT515, MIT525, MIT1025, and MIT1525 insulation resistance testers are compact, light 5 to 15 kV units for the diagnostic testing and maintenance of high voltage electrical equipment. They are ideal for original equipment manufacturers (OEMs) and industrial companies.
The MIT series has a full suite of test modes as well as on-board memory and the ability to stream data/download data to a PC/laptop. They also have rapid-charge batteries and operate from an AC source if the batteries are dead. Rapid charge batteries enable >60 minutes of testing after a 30-minute charge.
The MIT range includes:
- MIT515: 5 kV with IRT and DAR, but with no memory
- MIT525: 5 kV IRT with all test modes, including a ramp test plus advanced memory functions with recall to screen, RTC for time/date stamp of results, and USB drive to PC/PowerDB
- MIT1025: 10 kV IRT with all test modes, including a ramp test plus advanced memory functions with recall to screen, RTC for time/date stamp of results, and USB cable interface to PC/PowerDB
- MIT1525: 15 kV IRT with all test modes, including a ramp test plus advanced memory functions with recall to screen, RTC for time/date.
The MIT1525 is at the top of the range, and it performs insulation resistance tests up to 15 kV with a 30 TΩ maximum resistance and an accuracy of ±5 % from 1 MΩ up to 3 TΩ.
Safety rated to CAT IV, all these units are smaller and lighter than their predecessors, making them even easier to carry and store.
NEW
The patented PI predictor enables you to obtain 10 minute PI values in as little as 3 minutes! The new method starts to predict the final IR curve from 3 minutes into the test and as soon as the predictor is confident with the prediction, the test is stopped and the predicted value of the PI displayed. In most cases, this happens within 5 minutes, meaning the test time is typically halved!
Caractéristiques techniques
- Max resistance reading
- 30TΩ
- Power source
- Battery
- Power source
- Mains
Produits connexes
Dépannage
Unfortunately, lithium-ion batteries eventually wear out and can no longer accommodate a charge. This event is a common and, sooner or later, inevitable issue, but fortunately it is easily corrected. Replacement batteries are available from Megger, and you can quickly change one following the instructions in the User Guide.
Do a visual inspection of the unit, and don’t overlook the lead set. It is understandable to focus on the instrument and take the lead set for granted, but the leads are commonly knocked about from handling more than the instrument. In particular, the strain relief at the end of the lead becomes damaged - its absence is a strong indication that the lead set soon needs to be replaced. Damaged leads tend to affect the most negligible leakage currents first, so the instrument may not be able to indicate measurement into the tera-ohm (TΩ) range. This symptom means that the lead set should be repaired or replaced.
These are control and measurement boards post error codes. These appear on the display as “E” followed by a 1- or 2-digit number. The User Guide gives brief definitions. These are not user-adjustable. They indicate component failures or calibration resets that a Megger repair technician or authorised repair centre must perform.
Rough handling or bouncing around in a truck can cause this plastic insert to break. At this point, the display is merely hanging onto the top panel with no support. The display may still work for a time, but erratic performance will steadily increase. Contact your local Megger repair technician or authorised repair centre to repair the display.
This symptom indicates that the power supply transformer has broken off the power supply board, usually due to rough handling and/or dropping. The transformer, being relatively heavy, will come loose from its mountings. This breakage interrupts or terminates power to the circuitry, resulting in a ‘dead’ instrument. Contact your local Megger repair technician or authorised repair centre.
Interprétation des résultats de test
Insulation resistance readings should be considered relative. They can be quite different for one motor or machine tested three days in a row, yet it does not mean bad insulation. What matters is the trend in readings over a longer period, showing lessening resistance and warning of coming problems. Periodic testing is, therefore, your best approach to preventive maintenance of electrical equipment, using record cards or SW to trend the results over time.
Whether you test monthly, twice a year, or annually depends upon the equipment's type, location, and importance. For example, a small pump motor or a short control cable may be vital to a process in your plant. Experience is the best teacher in setting up the scheduled periods for your equipment.
We recommend making these periodic tests in the same way each time. That is, with the same test connections and test voltage applied for the same length of time. Additionally, we recommend performing tests at about the same temperature or correcting them to the same reference temperature. A record of the relative humidity near the equipment during the test is also helpful in evaluating the reading and trend.
In summary, here are some general observations about how you can interpret periodic insulation resistance tests and what you should do with the result:
Condition | What to do |
---|---|
Fair to high values and well maintained | No cause for concern |
Fair to high values but showing a constant tendency towards lower values | Locate and remedy the cause and check the downward trend |
Low but well-maintained values | Condition is probably acceptable, but you should investigate the cause of low values |
So low as to be unsafe | Clean, dry out, or otherwise recondition the insulation to acceptable values before placing equipment back in service (test wet equipment after drying out) |
Fair or high values, previously well-maintained but showing a sudden decrease | Make tests at frequent intervals until you locate and remedy the cause of low values; or until the values have become steady at a lower level but safe for operation |
The resistance of insulating materials decreases markedly with an increase in temperature. However, we’ve seen that tests by the time-resistance and step-voltage methods are relatively independent of temperature effects, giving relative values.
To make reliable comparisons between readings, you should correct the measurements to a base temperature, such as 20 °C, or take all your readings at approximately the same temperature.
A good rule of thumb is to halve the resistance for every 10 °C increase in temperature or, for every 10 °C decrease, double the resistance.
Each type of insulating material will have a distinct degree of resistance change with temperature. Factors have been developed, however, to simplify the correction of resistance values. Please refer to the document "Stitch In Time" to find such factors for rotating equipment, transformers, and cables (Section: Effect of Temperature on Insulation Resistance).