Guardian Hipot Analyzer – 19055
Hipot or dielectric withstand testing instruments are used for conducting electrical safety tests on electrical components and products to make certain they are in compliance with IEC, UL, TUV, CSA, EN and other electrical safety requirements. The Guardian 19055-C not only includes AC/DC/IR tests but also a new measurement technology – Corona Discharge Detection (CDD).
- 500V output rating
- Hipot: AC 5kV/100mA – DC 6kV/20mA
- Insulation: 5kVmax – 1MΩ~50GΩ
- Output Frequency: 50Hz ~ 600HZ
- Floating output complies with EN50191
- Corona Disharge Detection (CDD, 19055-C)
- Flashover Detection
- Discharge Level Analysis (DLA)
- Open/Short Check function (OSC)
- High Frequency Contact Check (HFCC)
- Ground Fault Interrupt
- Standard RS-232 Interface
- Optional GPIB & HANDLER Interface
- Key Lock when Fail
- Programmable Voltage and Test Limit
- CE Mark
- Supports A190301 8HV Scanning Box
- 2-Year factory warranty
Chroma’s Guardian 19055 Series Hipot Analyzers are designed for hipot tests and analysis of transformers, motors and other electronic components. The tests of AC/DC/IR can be programmed in AC 5kV/100mA – DC 6kV/20mA with 500VA output rating which complies with the EN50191 requirements. The Guardian 19055-C not only includes AC/DC/IR tests but also a new measurement technology – Corona Discharge Detection (CDD). Corona Discharge Detection and Discharge Level Analysis (DLA) are used to specify the Corona Discharge Start Voltage (CSV), Flashover Start Voltage (FSV) & BreakDown Voltage (BDV).
These functions provide useful data to verify the product’s insulation and increase the reliability of the product during manufacturing.
For Contact Checking during the hipot test, the Guardian 19055 Series is equipped with a High Frequency Contact Check (HFCC) besides the Open Short Check (OSC) function. By conducting the Contact Check during Hipot test, it can increase the test reliability and efficiency significantly. For convenience, the Guardian 19055 has a large LCD screen for operation. In addition, the GFI human protection circuit and Floating safety output prevents electrical hazard to the operator.
For Transformers: The internal winding of a transformer often endures unstable voltage for long periods when used under normal conditions. Over time, the insulation is affected if the primary side components are in a state of corona discharge. For example, most power transformers reserve an auxiliary coil for other circuits to use in the primary side as the figure shows. When it is used under Vp=750V for a period of time and if the manufacturing process included faulty insulating tape or tubing it would cause a continuous corona discharge. Insulation of primary winding would be compromised and burned out eventually due to the enameled carbonization.
For Motors: As industrial motors or EV motors are used for long hours and under varying environmental conditions such as temperature and humidity, features like high durability and reliability are most critical. Temperature is also one of the key factors to influence insulation. If corona discharge occurs in turn-to-turn and turn-to-ground, it would cause the insulation to deteriorate due to the increase in heat and material qualitative change. Adding Corona Discharge Detection in hipot testing exceeds the quality requirements for insulation by detecting units with poor insulation early thus reducing the defect rate caused by long-term usage. The image shows Corona Discharge in a motor.
Discharge Level Analysis for high voltage capacitors, safety capacitors, photocouplers and insulation materials:
When gaps or voids in the insulation medium happen in the manufacturing process, different electric fields will be formed and corona discharge will occur when the hipot test is conducted. The medium changes when such usage continue over time and quality issues will appear due to the faulty insulation.
Discharge Level Analysis
The dielectric withstanding voltage of components depends on materials and the manufacturing processes. For improving insulation in components, discharge levels should be defined including Corona discharge, Flashover and Breakdown. The Guardian 19055 is equipped with a Discharge Level Analysis mode (DLA) for defining the programming voltage, time, counts and limits.
The Guardian 19055 Hipot Analyzer provides discharge analysis of three levels. DLA mode will indicate the withstanding voltage depending on the different level limit beginning with Corona Discharge Start Voltage (CSV), Flashover Start Voltage (FSV), and Breakdown Voltage( BDV). R&D and QC personnel are able to improve insulation by discharge data collection and analysis.
All hipot and dielectric test equipment have the ability to detect a breakdown, and some have the ability to detect flashover (ARC), but only a few have the added ability to detect CORONA DISCHARGE. Although safety agencies have not included any requirement to measure the corona discharge in the safety test requirements, by accurately measuring the leakage current dynamically in very small levels, it is possible to determine if the unit is in one of the following conditions:
Corona Discharge: an electrical discharge brought on by the ionization of a fluid surrounding a conductor, which occurs when the potential gradient (the strength of the electric field) exceeds a certain value, but conditions are insufficient to cause complete electrical breakdown or arcing. Corona discharge may be an early symptom of an impending breakdown.
Flashover: an electrical breakdown of a gas that produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive media such as air. Vasily V. Petrov, a Russian scientist who discovered it in 1802, first described the phenomenon.
Breakdown: a rapid reduction in the resistance of an electrical insulator that can lead to a spark jumping around or through the insulator. This may be a momentary event (as in an electrostatic discharge), or may lead to a continuous arc discharge if protective devices fail to interrupt the current in a high power circuit.
The graph below shows the association of these three conditions:
Open/Short Check Function (OSC)
All manufacturers have faced problems with errors in test cable connection or shorts. Chroma solves this issue with its patented OSC function.
The open/short check function is used to check if the connection to the DUT is open (bad contact) or a short during the testing process. When an open contact occurs during testing, the test may result in a PASS for a product that may or should have FAILED. If there is a short in the DUT during testing, the instrument may be at risk with the high load current. Checking for opens and shorts during testing ensures efficient testing and protects the equipment.
In most cases the Device Under Test (DUT) will have some capacitance between the Input line and neutral connections with respect to AC Ground. By applying a alternating voltage and measuring the resulting current we can determine the impedance of the DUT based on its normal capacitance. If the connections are open the resulting AC current will be very low compared to the normal connection, and if the DUT is internally shorted the resulting AC Current will be much higher.
Ground Fault Interrupt (GFI)
Hipot and Dielectric Withstand test equipment can present an electrical shock hazard to the test operator. Test equipment manufacturers have included a GROUND FAULT INTERRUPT (GFI) circuit to help prevent the operator from being electrically shocked. A ground fault exists whenever currents i1 and i2 are not equal, as shown in the figure below.
When the current meter A1 and A2 detects the difference (i2-i1=iH) between the value i1 and actual i2 test current over high, the device cuts the power transiently to safely protect the equipment operator.
Because of the many safety agency standards, we can always be a good source of information and support when you have questions about safety test requirements and issues. For quick support, our applications engineers, and sales and service support people are readily available to help you.
|Guardian 19055||Hipot Analyzer (AC/DC/IR) – 500VA|
|Guardian 19055-C||Hipot Analyzer (AC/DC/IR/DLA/CDD) – 500VA|
|A190355||19″ Rack Mount Kit|
|A190356||GPIB Interface for Model|
|A190301||(1930A) 8HV Scanning Box [19055x]|
|A190708||ARC Verification Fixture|
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