ABB DCS 500B Description

Also see for DCS 500B: Operating instructions Service manual Service manual

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ABB DCS 500B Description Manual pdf 53 page image

Functional Software descriptionDCS 500 Software Description 45Tuning of CurrentRegulatorTuning of the regulator can be done either manually with responsetests or with autotuning function, which is activated by setting pa-rameter DRIVE MODE (1201) to 3, when the drive’s main contactoris open. After closing of the main contactor and starting of thedrive, the autotuning procedure for the armature current controllerwill start. The DRIVE MODE (1201) value is set to 0 when auto-tuning is completed. The autotuning proceeds without user inter-vention. Motor data have to be set correctly before autotuning isstarted. More information about tuning can be read in chapterStart-up.Firing AngleLimitationThe output signal of the regulator is the firing angle reference (1 =1°) ARM ALPHA (10401). Its minimum value is limited by means ofparameter:The maximum output voltage of the thyristor bridge is limited byparameter ARM ALPHA LIM MIN (413), default value =15The armature voltage is U = 1.35 * USUPPLY * Cos α, if thecurrent is continuous. α = ARM ALPHA.For example, if USUPPLY is 400 V AC, the maximum armaturevoltage is 1.35 * 400 V * Cos 15° = 521 V.The maximum firing angle is limited by parameterARM ALPHA LIM MAX (412), default value = 150. Do not changethis value without consulting ABB!Additional Com-mutation ReserveDXNThe commutation can not take place infinitely fast because of thenetwork reactance. The time for the commutation can be ex-pressed by the commutation angle u, which can be calculated us-ing formula:u = arc cos (cos α - Id / Ik ) - αwhere Ik = short circuit currentId = load currentUl = network voltageXl = network total reactanceExample It is wanted that a "weak" network can commutate 600 A current.The nominal voltage of the network is 380 V and frequency 50 Hz.Used transformer:20 kV/400 V, 500 kVARk = 0.0032 ΩLkm = 48.85 μH/phaseCable: lenght 50 m, 250 μH/km, Lkk = 12.5 μH/phase