The quality verification test items for Wound Components primarily are AC/DC Hipot tests and Insulation Resistance (IR) tests. The Chroma 19035 Wound Component EST Scanner Series perform these and other safety tests for motors, transformers, and heater related wound products. These scanners make for reliable quality control and efficient product control when implemented for quality verification by wound component manufacturers.
The Chroma 19035 Series supports 5kVac/6kVdc high voltage output to conform with withstand voltage test requirements for wound components, and has a maximum output current up to 30mA. The Insulation Resistance (IR) test measurement ranges from 1MO to 50GO, and voltage output can be up to 5kV; while the DCR test can measure the resistance parameters of wound components and test circuit connections (contact check) before the withstand voltage test is performed.
The 19035 Series also has powerful functions for Flashover detection and Open/Short Check (OSC), as well as programmable voltage and time parameters for various characteristics of DUTs for increased testing reliability and product quality.
Flashover Detection
The Chroma 19035 has the same Flashover detection as other Chroma EST testers. Flashover is the electrical discharge generated by high electrical fields inside or on the surface of insulation materials that cause the DUT to lose its insulation characteristics and form a transient or discontinuous discharge. It can cause a carbonized conductive path, or damage the product under test. Flashover cannot be detected by monitoring leakage current only. The change rates of test voltage and leakage current must be monitored in order to detect flashover, as its detection is one of the most indispensable test items for electrical safety testing.
Ground Fault Interrupt (GFI)
The requirements for test environments indicates that test equipment is to be equipped with an auto interrupt device, so Chroma built in a Ground Fault Interrupt (GFI) function. When the current meter A1 and A2 detect a difference (i2-i1 = iH ) between the value i1 and actual i2 test current over high, this device can cut the power transiently for protecting against electrical shock to the operator. It is not only according to safety standards but also provides additional safeguards for test personnel.
Open/Short Check OSC
The O.S.C. function is used to verify whether the connection is an open connection or that a short circuit exists between an instrument and DUT (device under test) before the Electrical Safety Test is performed. If there is a bad connection between the instrument and DUT, for instance a bad lead or relay oxidation, the test will also PASS. In some cases, the DUT has a short before testing. In this case, testing can lead to a broken test instrument due to the high load current. Therefore, our test devices check for open and short circuit conditions to ensure effective testing and protect instruments. Generally, the DUT have capacitive loads (Cx) from tens to thousands pF. If the connection is open, a capacitance will appear and then total capacitive load is lower then that in normal condition. If the connection is shorting, total capacitive load is higher then that in normal condition. Therefore, we can measure the value of capacitive load to check whether the contact is good or not.
High Speed Contact Check (HSCC)
HSCC mode is a new measurement technology for contact checks. It scans the circuit contact with multiple test points in a very short period of time. With this new feature, contact checks can be performed quickly prior to the Hipot test.
DCR Measurement 2W/4W
DCR measurement for two-wire/four-wire is one of the standard test items. The two-wire measurement is suitable for major DCR, whereas the four-wire measurement is suitable for minor DCR since it is more accurate.
Temp Compensation
Problems caused by temp differences will usually occur while measuring minor DCR values, when the temp difference and the measured resistance value will be different. With the Temp Compensation function that has been added to the 19035, the DCR is converted to the measured value under standard temp via temp coefficient conversion. Thus, the measured difference generated by temp difference is reduced.
DCR Balance
Checking DCR balance of motor windings is just as important as checking inductance balance of the windings. When the EMF drive of different windings are not matched the rotational torque force will be unbalanced causing additional shaft wobble, vibration and bearing wear which affects long term life of the motor. The DCR Balance calculates the difference between the max and min DCR of the windings and compares that value to an acceptable programmable level, which in turn gives a PASS/FAIL output result for DCR balance. The DCR Balance Test is an auxiliary test tool for motors which helps establish long-term reliability of motors.
Contact Check
DCR tests not only measures the resistance of the winding, but also checks the connections before the Hipot test. The Chroma Hybrid 19035 can perform DCR measurements on windings to check for external contact, and for capacitance lower than 20 pF between the test points in wound components.