Elma BM 251-252-255-257
side 48
Electrical specifications
Accuracy is given as +/- (% of reading number of digits) or otherwise specified @
23
o
C +/- 5
o
C and less than 75% R.H.
True RMS model BM257 ACV & ACA accuracies are specified from 5 % to 100 % of range
or otherwise specified. Maximum Crest Factor <3:1 at full scale & <6:1 at half scale, and
with frequency components fall within the meter specified frequency bandwidth for non-
sinusoidal waveforms
AC Voltage
RANGE
Accuracy
50Hz ~ 400Hz
60.00mV, 600.0mV
1.0% + 5d
6.000V, 60.00V, 600.0V, 1000V
CMRR: >60dB @ DC to 60Hz, Rs=1k
Ω
Input Impedance: 10M
Ω
, 50 pF nominal
AutoCheck
TM
_ACV (BM255 & BM257 only)
RANGE
Accuracy
50Hz/60Hz
1.000V ~ 1000V
1.4% + 5d
AutoCheck
TM
Lo-Z ACV Threshold:
> 1V nominal
AutoCheck
TM
Lo-Z ACV Input Impedance:
Initially approx. 2.5k
Ω
, 120pF nominal; Impedance increases abruptly within a fraction of a
second as display voltage is above 50V (typical). Ended up impedances vs display
voltages typically are:
15k
Ω
@100V
100k
Ω
@300V
250k
Ω
@600V
375k
Ω
@1000V
Ohm
RANGE
Accuracy
600.0
Ω
, 6.000K
Ω
, 60.00K
Ω
, 600.0K
Ω
0.5%+4d
6.000M
Ω
0.7%+4d
60.00M
Ω
1.2%+4d
Open Circuit Voltage: 0.45VDC typical