7.8.9.1 The injection unit REX060Injection RotorPSMBackplaneFront-plateBack view Front viewPowerconnectorIED andInjectionconnectorsPowerStatorRotorInjection StatorTop viewHMI with logic1 1 118185X11 X61 X81Injection switch1515X62 X82KeylockLEDInjection LEDIEC11000015-1-en.vsdIEC11000015 V1 ENFigure 126: Injection unit REX060The REX060 unit is a common unit that can be configured for either rotor or statorearth fault protection, or for both. The REX060 have separate modules for rotor andstator protection. The REX060 generate square wave signals, where one is used forinjection to the stator neutral point and the other to the field winding circuit (rotorcircuit), if configured for both stator and rotor protection. The injected voltage andcurrents are measured by the unit and amplified, resulting in voltage signals both forthe injected voltage and current, and adapted to the analogue inputs of IED. Theinjection unit REX060 shall be located close to the IED, preferably in the samecubicle.For the Sensitive rotor earth fault protection, there are some settings necessary forREX060:• System frequency: 50/60 Hz• Injected frequency for rotor circuit injection is settable in 1 Hz steps 75 – 250 Hz.• Gain factor in four stepsREX060 will also continuously check the measured signal for detection of saturationwhich could cause error in the evaluation in IED. If saturation level is reached a binarysignal, connected to IED, is activated. Also other errors in the injection circuit willinitiate a binary signal to IED for blocking of the function.Rotor injection output is protected against high voltages by a relay blocking theinjection circuit. This blocking remains blocked by stored status in non-volatilememory.The output is also protected by a fuse. If this fuse is blown, it is caused by externalvoltage source, since the injection unit cannot provide enough energy to blow thisfuse.Refer to the Hardware section in this manual for a detailed description of REX060.Section 7 1MRK502052-UEN BImpedance protection286Technical manual
