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Application of the article
Insulation resistance
A case study
Measurement tools:雷竞技appFluke 1550 c high voltage insulation resistance tester
Operator:ASI Robicon, high-power VFDS manufacturer
Perform the test:Silicon controlled rectifier voltage, silicon controlled rectifier thermal test, IGBT switch, capacitance
ASI Robicon Perfect Harmony water-cooled variable frequency drives (VFDS).
Tom Lasek is ASI Robicon a field engineers, the company is a leading high power solid state variable frequency drive manufacturer, support up to 20000 HP industrial ac motor, the control of the input voltage of 13800 V.Lasek duties include high power drive system of the installation/commissioning, general preventive maintenance and fault diagnosis.He almos雷竞技appt daily use Fluke 1550 c high voltage insulation resistance tester:
- Insulation resistance testing and documentation records, for commissioning and start-up of the system.
- The high pressure of high power drive device fault diagnosis.
This case will be introduced in detail the high pressure components and Lasek 30 years of career development capacity test method.
By 1550 c in periodic preventive maintenance process as a high voltage component tester, Lasek can timely found defective components, to prevent its failure.To prevent early failure for both ASI Robicon also save time and money for its customers.
Silicon controlled rectifier voltage test
雷竞技appFluke 1550 c high voltage insulation resistance tester can quickly determine the relative quality of nonlinear devices in high power solid state power/weak link: SCR (silicon controlled rectifier semiconductor) and high power devices IGBT.General solid element tester adopts low voltage, low current test source, usually can't locate the damaged components, especially under the load may collapse.
methods
- Connect the components with all separated, to ensure the accuracy of reading.
- At the beginning of the 1550 c set on high pressure, test and record the readings.
Silicon controlled rectifier reading sample.
The results of
- In test forward bias and reverse bias (anode to cathode), if the silicon controlled rectifier is damaged, the readings will appear bigger difference.
- New silicon controlled rectifier in the direction of the two readings (about 100 MW) is almost equal.
- If the high power thyristor rectifier reading less than 5 MW, said damaged, should discard it./ li >
- If the reading on the silicon controlled rectifier in one direction for 50 MW, 200 MW, in another direction for 10 MW to 50 MW (difference 4:1), in May when load self-locked (rather than the expected trigger point trigger in time, will be random trigger open).This kind of situation is very bad.It will cause extreme current pulse in the power supply, can cause by the power supply in dc motor commutator flashover.
Silicon controlled rectifier thermal test
If the element has physical damage, you may need to remove their actual, thermal test.
methods
- S雷竞技appets the Fluke 1550 c to plant actual rated voltage.480 V VFDS (variable frequency drive) used on most of the ASI Robicon silicon-controlled rectifier rating of 1400 V.In the medium voltage (2300 V and 4160 V) on the drive also use 3000 V serial device.
- Device at low temperature, read the forward and reverse two readings.
- In high temperature box components heated to 180 ° F, and repeated tests.
The results of
If the leakage is as high as 50% or more, the device must be discarded.
Traditional test silicon-controlled rectifier, if not short circuit, argues that there is no problem.Lasek, said that this assumption is completely wrong.ASI Robicon when maintenance silicon-controlled rectifier power supply, the goal is to maximize reduce faults and downtime, instead of minimizing the parts cost of maintenance.
Any device at its rated voltage, if reading performance as change, fluctuation, is not stable, should be thought imminent failure, and isolate them.Unstable readings said internal arc is damaged, or lock/conduction semiconductor itself.
IGBT switching device testing
IGBT switching device also can undertake thermal test, but because of the negative resistance characteristics of diode, only in one direction (positive) to inspect.Also can undertake thermal test of high power diode (compare the change of the low and high temperature readings).In general, compared with silicon controlled rectifier (reading general for 200 MW and 700 MW), the resistance of the diode is much higher, leakage current is much smaller.
If the silicon controlled rectifier reading in two directions are 20 MW, there is no problem;But if a direction readings of 80 MW, and another direction for 20 MW, indicates the failure.New silicon controlled rectifier readings in both directions are usually 100 MW and 200 MW, the direction of the two difference within 50%.
Capacitance test
Lasek has used 1550 c of the adjustable function test high voltage capacitor.
methods
For several identical capacitor recharged, and compare the charge to similar to the time needed for reading.
Capacitance reading sample.
The results of
- If the capacitor charging extremely fast, may already be open.
- If reading is up, down, repeatedly said capacitance internal flashover may occur.
Please remove the and replace the device.
