MAR-APR 2019

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INTECH MARCH/APRIL 2019 39 Certification Review | association news ISA Certified Control Systems Technician (CCST) program CCST question If the proportional band on a controller is 100 percent, then the controller gain is equal to: A. 0.50 B. 0.20 C. 1 D. 100 CCST answer The correct answer is C, "1." The propor- tional band is defined as the amount of change in input (or deviation), as a per- cent of span, required to cause the con- trol output to change from 0 percent to 100 percent. ISA Certified Automation Professional (CAP) program CAP question Why must voltage be reduced along with frequency in a variable frequency speed controller? A. to let the motor cool off B. because of capacitive reactance C. to maintain the volts/hertz ratio D. to keep the motor from overspeeding CAP answer The correct answer is C, "to main- tain the volts/hertz ratio." The speed of the motor is controlled by chang- ing the frequency applied to the motor: RPM = (Frequency • 120) / (# of poles in the motor) Varying the frequency affects both the motor speed and the strength of the mag- netic field. When the frequency is lowered (slower motor speed), the magnetic field increases, and excessive heat is gener- ated. When the frequency is in creased (higher motor speed), the magnetic field decreases, and lower torque is produced. In order to keep the magnetic flux con- stant, the V/Hz ratio must remain con- stant. This keeps torque production sta- ble, regardless of frequency. As frequency changes, we want to maintain a constant flux density to maintain the torque devel- oped by the motor. Reference: Trevathan, Vernon L., A Guide to the Automation Body of Knowledge, Second Edition, ISA, 2006. Certified Automation Professionals (CAPs) are responsible for the direc- tion, design, and deployment of sys- tems and equipment for manufactur- ing and control systems. Certified Control System Technicians (CCSTs) calibrate, document, trouble- shoot, and repair/replace instrumenta- tion for systems that measure and con- trol level, temperature, pressure, flow, and other process variables. Gain is a unitless number that defines the ratio of the change in output, due to proportional control action, to the change in input, in percent of span. From the above definitions: PB = [∆ INPUT / ∆ OUTPUT] × 100 (1) and GAIN = ∆ OUTPUT / ∆ INPUT (2) Combining equations 1 and 2: PB = 100 / GAIN or GAIN = 100 / PB For a PB = 1: GAIN = 100 / 100 = 1 Reference: Goettsche, L. D. (Editor), Main- tenance of Instruments and Systems, Sec- ond Edition, ISA, 2005. New CAPs and CCSTs Name Company Location Level 1 David M. Gwin None U.S. Geoffrey B. Rousseau None U.S. Randy A. Dugger None U.S. David N. Jones None U.S. James E. Anderson None U.S. Robert G.W. Whalen None U.S. Hiram G. Page None U.S. Russell Daniel Reed Holly Frontier U.S. Evan B. Williamson None U.S. Travis D. Russell None U.S. Brandon Weibley Prime Controls U.S. Angel J. Hernandez None U.S. Joel M. Martinez None U.S. Marco A. Venegas Orange County Sanitation District U.S. Henry Ng Orange County Sanitation District U.S. Albert Navarro None U.S. Gholamrezaei Reza Orange County Sanitation District U.S. Ryan M. Raiford Orange County Sanitation District U.S. Level 2 Timothy C. Secrest None U.S. Joshua A. Smith None U.S. Matt A. Hayes None U.S. Justin M. Kovalski None U.S. Jason W. Gerard None U.S. Rick M. Mirolla None U.S. Edward V. Keen None U.S. Dominic D. Duffert None U.S. Pedro N. Gulbe None U.S. Jeffrey P. Campbell None U.S. Jan A. Gramley None U.S. Joseph D. Davis None U.S. Robert C. Davis None U.S. Benjamin J. Smith None U.S. Mitch E. Maloof None U.S. Certified Control System Technicians Certified Automation Professionals Name Company Location Saad Rehman Hashmi Qatar Chemical Co. Ltd. Qatar Servio Uribe None U.S. Michael J. Bartlett None U.S. Sudhakar Rajendran WorleyParsons Abu Dhabi Arthur Eugene Nichols None U.S. Tom J. Hilty None U.S.

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