ABB DCS 500B Description

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ABB DCS 500B Description Manual pdf 51 page image

Functional Software descriptionDCS 500 Software Description 43Torque Step [TORQ STEP] (2409) input is available for testing the currentregulation or for direct control of the current regulator.Output Limitationand its IndicationOutput signal OUT (12402) can be limited by internal signals[TORQ MAX2] and [TORQ MIN2] in the function block TORQUE /CURRENT LIMITATION.Output IN LIM (12404) is in logical state 0, when the input of thelimitation block is within the TORQMAX2 and TORQMIN2.CURRENT_CONTROLfunction blockTorque / CurrentReference Selec-tionThe current reference is formed by dividing [TORQ REF] (401) bythe FLUX REF1 signal according to formulaCurrent = Torque / FluxThe current reference can be connected to input [CURR REF](402). Selection between these two references is made with pa-rameter REF TYPE SEL (405), logical state 1 selects the currentreference.Current Re-sponse TestA current regulation response test can be done by connecting thestep reference to input [CURR STEP] (403).RegulationBlockingThe current regulation can be blocked by setting input [BLOCK](404) to logical state 1.Armature CurrentScalingThe torque reference from the torque reference selector is con-nected to the current reference by means of the flux reference sothat with nominal flux and nominal torque the current reference willbe equal to nominal current of the motor. The scale of the currentreference is 4095 == nominal current of motor I MOTN A (502).Current Refer-ence Rise TimeThe rise time of the current reference can be adjusted by parame-ter ARM CURR REF SLOPE (406), scaling 1 = 1ms. This is used,for example, if a too fast rise time causes problems in the motorcommutator.Current Refer-ence LimitationAfter the slope the armature current reference goes through thecurrent limiter. Positive/negative limits of the current reference arebased on parameter ARM CURR LIM P (2307) and ARM CURRLIM N (2308) or on a speed-dependent current limitation.Current Differ-ence AlarmThe difference between the ARM CURR REF and the ARM CURRACT (10502) goes directly to the current regulator. If the differencebetween these values is larger than 20% (from nominal 4095) andthis situation remains at last 5 seconds, then the ARM. CURR.DEV. ALARM will be given.