User Manual

28 GMC-I Messtechnik GmbH
V/Hz, , Temperature, and A/Hz Measurements
5 Measurements
5.1 Voltage Measurement
Notes Regarding Voltage Measurement
• The multimeter may only be operated with installed batteries or re-
chargeable batteries. Dangerous voltages are otherwise not indi-
cated, and the instrument may be damaged.
• The multimeter may only be operated by persons who are ca-
pable of recognizing contact hazards and taking the appropriate
safety precautions. Contact hazards exist anywhere, where
voltages of greater than 33 V (RMS) may occur. The test
probes may only be gripped up to the finger guard. Do not
touch the metallic test probes under any circumstances.
• Avoid working alone when taking measurements which involve
touch hazards. Be certain that a second person is present.
• For the METRAHIT ULTRA, maximum allowable voltage between the
connector sockets and ground is 600 V for measuring cate-
gory III and 300 V for measuring category IV.
• Be prepared for the occurrence of unexpected voltages at de-
vices under test (e.g. defective devices). For example, capaci-
tors may be dangerously charged.
• No measurements may be made with this instrument in electri-
cal circuits with corona discharge (high-voltage).
• Special care is required when measurements are made in HF
electrical circuits. Dangerous pulsating voltages may be pres-
ent.
• Be aware of the fact that dangerous voltage spikes are not displayed
during measurement with the low-pass filter. We recommend mea-
suring voltage without the low-pass filter first, in order to be able to
detect any dangerous voltages.
• Be absolutely certain that the measuring ranges are not over-
loaded beyond their allowable capacities. Limit values are included
in section 8, “Technical Data”, in the table entitled “Measuring
Functions and Measuring Ranges” in the “Overload Capacity”
column.
• 300 mV range: Thermovoltages occur in the event of tempera-
ture fluctuation, which appear as additional voltage offset. It
may be necessary to repeat zero offsetting in order to achieve
the specified degree of accuracy.
Scope of Functions, Voltage Measurement
1
A 1 kHz low-pass filter can be used in this case, in order to filter out high
frequency pulses of greater than 1 kHz, for example when performing
measurements at pulsed motor drives.
Function
METRAHIT ULTRA
V AC / Hz TRMS, dB (Ri 5 M)
1

V AC / TP-Filter 1 kHz
1)
(Ri = 5 M) TRMS

V AC+DC TRMS / TP-Filter (Ri =5 M)

V DC (Ri = 10 M)

Pulse frequency, MHz @ 5 V TTL

Duty cycle as %

Voltage level measurement, dB @ V
AC
@ V
AC+DC
Frequency bandwidth
100 kHz