Agilent Technologies U2741A Podręcznik Użytkownika Pobierz pdf (Strona 72)

54 U2741A User’s Guide

3 Measurement Tutorial

If power dissipation is a problem, you should select the

digital multimeter's next higher measurement range to

reduce the errors to acceptable levels. The following table

shows several examples:

Errors in high resistance measurements

When you are measuring large resistances, significant errors

can occur due to insulation resistance and surface

cleanliness. You should take the necessary precautions to

maintain a "clean" high- resistance system. Test leads and

fixtures are susceptible to leakage due to moisture

absorption in insulating materials and "dirty" surface films.

Nylon and PVC are relatively poor insulators (10

Ω) when

compared to Polytetrafluoroethylene (Teflon/PTFE) insulators

(10

Ω). Leakage from nylon or PVC insulators can easily

contribute a 0.1% error when measuring a 1 M

Ω resistance

in humid conditions.

Ta bl e 3 - 2 Power dissipation for various resistance ranges

Range Test current DUT

power at full scale

100 Ω 1 mA 100 mW

1 kΩ 0.83 mA 689 mW

10 kΩ 100 mA 100 mW

100 kΩ 10 mA 10 mW

1 MΩ 900nA 810 nW

10 MΩ 205 nA 420 nW

100 MΩ 205 nA ||10 MΩ 35 nW

User's Guide.book Page 54 Friday, August 8, 2008 9:11 AM

1 2 ... 67 68 69 70 71 72 73 74 75 76 77 ... 90 91

Brak uwag

Agilent Technologies U2741A Podręcznik Użytkownika Strona 72