13.6.6 100% Stator ground fault protection, 3rd harmonic basedSTEFPHIZ (59THD) SEMOD158990-3 v4Prepare the IED for verification of settings outlined in Section "Preparing the IED toverify settings".13.6.6.1 Testing SEMOD158990-8 v3The protection function uses measurement of the third-harmonic voltages in the neutralpoint of the generator and on the generator terminal (broken delta voltage transformerconnection to the IED).The test set shall be capable to generate third-harmonic voltages. One voltage (VN3) isconnected to the residual voltage input related to the terminal side of the generator. Thesecond voltage (VN3) is connected to the voltage input related to the neutral of thegenerator. The angle between the injected third-harmonic voltages shall be adjustable.en07000127_ansi.vsdV3NV3TANSI07000127 V1 EN-USFigure 61: Typical phasor diagram for third harmonic voltages for healthy machine1. Inject the following voltages: V3T = 15 V, V3N = 5 V and the angle between thevoltages = 180°. Check the monitored values of the following analogue signals:E3 (the magnitude of the third-harmonic induced voltage in the stator), V3N: 5 V(the magnitude of the third-harmonic voltage measured at the neutral side of thegenerator), V3T: 15 V (the magnitude of the third-harmonic voltage measured atthe terminal side of the generator) and ANGLE: 180° (the angle between thethird-harmonic voltage phasors V3N and V3T). The value of E3 should be close tothe following value:1MRK 502 073-UUS A Section 13Testing functionality by secondary injectionGenerator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062 229Commissioning manual
