The MK-12.8A-4600 Eccentric Mass Shaker System by ANCO Engineers, Inc. consists of an eccentric mass shaker, a drive motor, a frequency inverter with a remote operator's station, interconnecting cabling, and flexible shafting. The system is portable and can be disassembled into individual elements and transported.
The eccentric mass shaker consists of two matched sets of weights, a 4,600 lb-in (520 kN-mm) eccentricity set and a 980 lb-in (110 kN-mm) eccentricity set. The force output is limited to 10,000 lb (44 kN) continuously and 20,000 lb (89 kN) intermittently at frequencies less than 10 Hz with the large weight set installed. The small weight set must be used if the system is operated in the 10-20 Hz range. Eccentricity of the shaker is continuously adjustable over the ranges of 0-980 lb-in (0-110 kN-mm) and 0-4,600 lb-in (0-520 kN-mm). The shaker is powered by a 10-hp (7.4 kW), 6-pole (1200 rpm) induction motor.
The inverter rectifies 230-volt, 3-phase, 60-Hz line current to a direct current and constructs a pulse width modulated motor drive current whose frequency and voltage can be varied and controlled. The maximum output current frequency can be selected to be either 60 Hz or 120 Hz permitting either 10 Hz or 20 Hz full-speed shaker operation.
Running speed of the shaker is controlled either by rotation of a 10-turn potentiometer or by application of an external 0-9.0 volt dc signal. The shaker can either be operated from the inverter or from a remote operator's station. Cabling permitting, a 100 ft (30 m) separation between the inverter and the remote operator's station is provided.`
The NEES@University of Nevada, Reno equipment site is funded in part by the Geoge E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Program of the National Earthquake Hazards Reduction Program (NEHRP) of the National Science Foundation (NSF) under Award Number CMMI-0927178.