Effects of intermittent and constant punishment on resistance to punishment in a free operant situation for the albino rat.

Trained male Wistar albino rats (10 experimental and 9 control Ss) to barpress for food reinforcement in a 2-bar cyclic response chain situation. Responding on 1 bar led also to a punishment (footshock) on either an intermittent or constant schedule. Both punishment schedules led to increased responding on the nonpunished bar and to initial response suppression followed by recovery on the punished bar. For Ss on the intermittent schedule, the response increase on the nonpunished bar was seen only after a punishment on the other bar. Similar effects were found for transfer time between the 2 bars. The effects of punishment on response to both bars were more pronounced for the intermittent punishment groups. Results are discussed in terms of the motivational constructs of A. Amsel and of R. K. Banks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Voltages to ground in load-commutated inverters

Load-commutated inverter (LCI) drives are well suited to the starting and variable-speed operation of large fans, pumps, and compressors used in the petroleum industry. The origin and magnitude of the voltages to ground found in these types of drives are introduced and explained. The voltage to ground in most of the LCI circuit depends on bridge firing angles and can reach a maximum value as high as 2.4 p.u. (per unit) of rated. An analysis of this phenomenon and an algorithm for predicting the magnitude of the voltage as a function of machine voltage, and bridge firing angles is presented. Test results are included for validation of the analysis. How system grounding and DC link reactance can be used to reduce the magnitude of the elevated voltage to ground and transfer it to less devices is discussed