Test Your Motor Control IQThis quiz will help test your knowledge of a duplex pump controller.

T his month, we’ll wrap up our testing of theduplex pump controller circuit by askingyou to select the best description for the

50 December 2000 • EC&M • www.electricalzone.com

motor iq quiz

Baran is owner of Starrats Technical Services, Riverside,Ill. and former electrical controls instructor at CoyneAmerican Institute in Chicago. You can reach him by mailat Starrats Technical Services, P.O. Box 436, Riverside, IL60546; by e-mail at STARRATS@COMPUSERVE.COM;by phone at (708) 484-2477; or visit his Web site athttp://ourworld.compuserve.com/homepages/starrats.

By Larry Baran, Motor IQ Columnist

circuit conditions listed. Select all that apply, andonly one circuit condition is in effect at a time.

Consider the points A, B, C, D, E, and F asreference points. Refer to the wiring schematic, andassume the disconnect is closed and the motors andtransformer are fed by a 480V/3Ø/60 Hz powersource. Have fun, and don’t cheat!

Circuit Conditions (Part 1):1. Point F is open.2. OL1 contact is open.3. OL2 contact is open.4. Fuse F4 is blown.5. Fuse F3 is blown.6. Fuse F2 is blown.

Circuit Conditions (Part 2):Sometimes, it’s useful to use a jumper to bypasstrouble. But serious damage to equipment and per-sonal injury can result if you add jumpers without acomplete understanding of the consequences.

1. Points X1 and A are jumpered.2. Points X2 and A are jumpered.3. Points X1 and D are jumpered.4. Points X1 and E are jumpered.

Descriptions:A. M1 coil never turns on.B. Pump Motor 1 never turns on.C. Pump Motor 1 receives power, but single phases.D. A fuse opens.E. Control circuit short-circuit protection is com-promised.F. The pumps do not alternate.G. A pump turns on only when Float Switch 2 closes.H. Overload protection (OL1) does not work.I. Pump Motor 2 never turns on.J. Motor starts after a time delay.K. CR coil does not energize.

Answers:

(Part 1):1.F2.A, B, F, G, K3.F, I, P4.A, B, F, I, K, P5.A, B, F, I, K, P6.C, M, Q

(Part 2):1.E, F2.A, B, D, F, I, K, P3.E, F, N, G4.E, F, O, K, G

L. Overload protection (OL2) does not work.M. Pump Motor 2 receives power, but single phases.N. Pump Motor 1 turns on without the float switch.O. Pump Motor 2 turns on without the float switch.P. M2 coil does not energize.Q. An overload may trip.