Kiểm tra & Khắc phục sự cốCâu 505 / 521
You must measure current on a circuit feeding electronic (nonlinear) loads such as LED drivers and VFDs. Which meter feature gives an accurate reading?
a.A true-RMS meter
b.An averaging (non-true-RMS) meter
c.An analog swinging-needle meter only
d.Any meter reads distorted waveforms accurately
Giải thích
Nonlinear loads draw distorted, non-sinusoidal current, and only a true-RMS meter computes the real heating value accurately. Averaging meters (b) assume a clean sine wave and under- or over-read on distorted waveforms. An analog meter (c) is also averaging-type, and not all meters handle distortion (d).
Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- A conductor with 0.2 ohms of resistance carries 15 A. How much power is dissipated as heat in that conductor?
- A homeowner reports a 'weird' outlet. Which instrument most quickly indicates common miswires (open ground, open neutral, reversed polarity) at a 120 V receptacle?
- Two identical 60 W, 120 V lamps are accidentally wired in series across 120 V. Approximately what voltage will a DMM read across each lamp, and how will they glow?
- A 6 ohm and a 3 ohm resistor are connected in parallel. What total resistance should an ohmmeter read?
- During commissioning you want to confirm that a metal equipment enclosure is effectively bonded. Which check best verifies a low-impedance bond to ground?
- In a series circuit, 24 V is applied across a 4 ohm and an 8 ohm resistor in series. What voltage will a DMM read across the 8 ohm resistor?
Cập nhật gần nhất: · quy trình kiểm tra
Đội Ngũ Biên Tập PrepPass · Đối chiếu với California CSLB C-10 Electrical Trade Examination · Quy trình kiểm tra