EST case studies
EST · Put your knowledge to work in context.
The ETA International Electronics Systems Technician (EST) credential is one of the vendor-neutral, industry-recognized certifications offered by ETA International, a not-for-profit 501(c)(6) association founded in 1978 by electronics technicians. ETA states that its certifications are accredited by the International Certification Accreditation Council (ICAC) and aligned to the ISO 17024 standard, and that they are accepted by employers and listed on the U.S. The EST case studies are 5 cases and about 2,417 words.
1Intermittent Voltage Sag on a 24 V Control Bus
A technician maintains a 24 VDC control cabinet feeding eight solenoid valves through a shared 18 AWG bus. The supply is rated 5 A with foldback current limiting.
511 words, about 3 min2Choosing a Meter for a 480 V Motor Branch
An electrician must verify phase-to-phase voltage and check for a suspected loose neutral on a 480 V three-phase motor branch feeding a 15 kW pump. The available instruments are: a CAT II 600 V digital multimeter, a CAT III 600 V clamp meter, a CAT IV 300 V handheld, and a CAT III 1000 V true-RMS meter with a 10 A current range.
485 words, about 2 min3Link Budget Failure on a 5.8 GHz Point-to-Point Link
A 5.8 GHz point-to-point link spans 3.2 km between two rooftops. Each end uses a 23 dBi dish and a radio with 20 dBm transmit power and a receiver sensitivity of -85 dBm at the required data rate.
463 words, about 2 min4Fiber Run Fails OTDR Acceptance After Installation
A contractor installs 1.8 km of single-mode OS2 fiber between two buildings using a mix of indoor riser cable and outdoor loose-tube cable, joined at an entrance facility by a fusion splice. There are LC connectors at both ends and one splice.
470 words, about 2 min5Nuisance Trip on a Refrigeration Circuit After Maintenance
A maintenance tech services a walk-in cooler. After replacing a contactor and re-tightening line-side lugs, the compressor starts but the circuit breaker trips after about 90 seconds.
488 words, about 2 min