HP 34401A MULTIMETER

Transcription

1 HP 34401A MULTIMETER Produced by GMI Engneerng & Management Insttute & Hewlett-Packard Company HP 34401A Multmeter 6 1/2 dgt, hgh performance dgtal multmeter AC/DC voltage measurements AC/DC current measurements 2 and 4 wre resstance measurements Frequency and Perod measurements Math functons 1

2 Safety Tps Protect Yourself: Avod contact wth Voltage or Current Source. 1) Use shrouded test leads and allgator clps. 2) Connect leads to multmeter frst. 3) Do all normal connect/dsconnect at source. 4) Famlarze yourself wth the manual. Safety Tps Protect Instrument 1) Inductve Devces (e.g. transformers, chokes/nductors) nduce very hgh transent voltages. 2) Measurng resstance: Avod contactng probes wth lve crcuts when n resstance modes. 3) Measurng Current: Do not connect probes across voltage source. 2

3 Startng Multmeter To perform a complete self-test, hold down the shft key for more than fve seconds as you turn on the multmeter. The dsplay wll ndcate whether test passed. Error messages wll be dsplayed f a falure occurs mvdc Menu at a Glance Menu s organzed n a top-down tree structure wth 3 levels To turn on menu Shft On/Off To move left or rght To move up or down To enter command Auto / Man A: Meas Menu B: Math Menu C: Trg Menu D: Sys Menu E: I/O Menu F: Cal Menu 1: AC Flter 2:Contnuty 1: Read Hold 1: HP-IB ADDR 1: Mn-Max 1: RDGS Store 1: Secured 3

4 Math Functons To make null (relatve) measurement To store mn/max readngs Null Mn Max To make db measurements Shft db db = readng n dbm - relatve value n dbm To make dbm measurements Shft dbm dbm = 10*Log 10 (readng 2 / reference resstance/ 1mW) Lmt testng (Access through Menu) Trggerng Auto-trgger: Contnuously takes readngs at fastest rate possble for present confguraton. Default. Sngle trgger: Manual trgger by pressng Sngle One readng or specfed number of readngs (Sample count). Number of samples: Number of readngs meter takes wth each trgger: 1 to 50,000. Default s 1. Readng hold: Select by pressng Shft Auto/Hold Captures and holds a stable readng on the dsplay. 4

5 Measurng DC Voltage VDC V p-p AC 1 VDC * Note measurement ndcates only DC porton of sgnal Range and Resoluton Range 100 mv 1 V 10 V 100 V 1000 V (750 VAC) Maxmum Resoluton 100 nv 1 µ V 10 µ V 100 µ V 1 mv (750 µ VAC) 5

6 Resoluton Choces & Integraton Tme Integraton Tme** Resoluton Choces Default.02 PLC Fast 4 Dgt.2 PLC Fast 5 Dgt 1 PLC * Slow 4 Dgt 10 PLC * Slow 5 Dgt * Fast 6 Dgt 100 PLC Slow 6 Dgt Fastest, Least Accurate Slowest, Most Accurate * Equvalent to Pressng Dgts key on front panel. **In Power Lne Cycles (PLC). Integraton tmes of.02 and.2 do not provde power-lne nose rejecton characterstcs. A/D converter Measurng AC Voltage AC to DC converson: DCV proportonal to AC RMS AC to DC converter AC amplfer/ attenuator Couplng capactor blocks DC; only lets AC sgnal through mvac V p-p AC 1 VDC * Note measurement ndcates only the AC porton of sgnal 6

7 AC Flter Frequency Range* Tme to settle 3 Hz and above Slow 7 sec. 20 Hz and above Medum 1 sec. 200 Hz and above Fast 0.1 sec. *Selectable through the measurement menu AC-Couplng vs. DC-Couplng AC-Couplng-Advantage *Removes DC Porton of Sgnal AC-Couplng-Dsadvantage *Low Frequency waveforms can be cut-off 7

8 Vrms: Root-Mean-Square Instantaneous power to a resstor s: Average power to a resstor s: Pavg = Vrms2 R = to+t 1 R( 1 v(t) T ) 2 dt Solvng to+t 1 for Vrms: Vrms * v( t) 2 dt T to A gven Vrms AC has the heatng (power) effect of a VDC wth the same value. to P = v(t) 2 R Voltage measurements Peak to Peak Vrms Vp Vpp Vrms = Vp *.707 (Sne wave) 8

9 Measurng Current Internal current shunt (same for ac and dc) I = V r ADC r V R Iac+ Idc + SHIFT DC I = Measure DCI SHIFT AC I = Measure ACI * NEVER HOOK CURRENT LEADS DIRECTLY ACROSS A VOLTAGE SOURCE R X Iac+ Idc Break crcut to measure I + Measurng Resstance 2-wre kω 1 kω * Press Ω 2W * Resstance measured ncludes lead resstance * To elmnate the lead resstance: - Short leads together - Press NULL - Lead resstance wll be subtracted from readng 9

10 Measurng Resstance 4-wre kω 1 kω * Turn off Null * Press SHIFT Ω4W * No error due to lead resstance 4-Wre Resstor Measurement Hgh- Input =0 Hgh- Sense R =0 Hgh Z V Low- Sense Itest Low- Input V = Itest * R V R = Itest 10

11 Contnuty Test & Dode Check + - Open or Closed Crcut. Forward Bas Cont Shft = Contnuty test = Dode check Measurng Frequency & Perod ,0 khz 33 khz Freq Shft = Measure Frequency Perod = Measure Perod 11

12 Frequency and Perod Perod f1( t) Frequency = 1/Perod Rato Measurements DCV : DCV + Sgnal Voltage + Reference Voltage dc sgnal voltage Rato = dc reference voltage *To enable rato measurements, use the MEAS menu. 12

13 Voltage RMS vs. Peak Waveform Vrms Vp sne trangle square DC * Peak voltage = 1/2 of Peak to Peak voltage Hgh Z Termnaton SIGNAL SOURCE Ro=50 Ω Vs MEASURING DEVICE R C Vm Zc 1 j 2π fc Zn R Zc R + Zc Hgh Resstance Vs = 1 + Ro Zn Vm.... for very large Zn, Vs Vm As frequency ncreases, Zn decreases For less than 1% error Zn > 100 Ro 13

14 50 Termnaton Ω SIGNAL SOURCE Ro=50 Ω Vs MEASURING DEVICE 50 Ω R C Vm Vs Vs 1+ 50Ω Vm 50Ω 2 Vm Hgh Resstance Vm 1 2 Vs *Vm wll not equal Vs, f Zn = Ro, but the rato between them s 2:1. Remote Interface HP-IB (IEEE-488) Address: Can be any value between Factory set at 21. Address 31 s talk only mode. Adjustable only through the I/O menu. RS-232 Interface: Baud rate must be selected (I/O menu): 300, 600, 1200, 2400, 4800, or Party selecton (I/O menu): Even or Odd Programmng Languages HP-IB RS-232 SCPI Language HP 3478A Language Not allowed Fluke 8840A Language Not allowed 14

15 Loadng Errors (DC volts) Rs HI Ideal meter Vs LO R Vs = deal DUT voltage Rs = DUT source resstance R = multmeter nput resstance (10 MΩ or > 10 GΩ) Error(%) = 100 * Rs Rs + R Leakage Current Errors Rs HI Vs R Ib C LO Ideal meter Ib = multmeter bas current Rs = DUT source resstance C = multmeter nput capactace Error(v) Ib Rs 15

16 Common Mode Rejecton (CMR) HI Ideal meter Vtest Rs LO Vf R > 10 GΩ Vf = float voltage Rs = DUT source resstance mbalance R = multmeter solaton resstance Vf * Rs Error(v) = Rs +R Nose caused by Ground Loops Rl HI Ideal meter Vtest Rl LO R > 10 GΩ Vground Rl = lead resstance R = multmeter solaton resstance Vground = voltage drop on ground bus 16

17 The DIGITAL MULTIMETER Hnts for Accurate Measurements: Measure as near full scale as possble Use a Rato measurement whenever possble. Before measurng, short the test leads together to check for offsets. (Excepton: RMS AC measurements) Where to get more nformaton HP 34401A User s Gude HP 34401A Servce Gude For on-lne techncal nformaton call HP Drect at