444-2 Low Voltage Micro-Ohmmeter
Measures from 50 Micro-Ohm to 20 Ohms
Simpson’s high precision Model 444-2 has been redesigned for added ESD
immunity and longer battery life. The model 444-2 Micro-Ohmmeter measures
resistance from 50 micro-ohm to 20 ohms. It measures using an extremely small
test voltage (100 microvolt maximum) and a four wire measurement technique.
The resistance reading is indicated on a 4- 1/2 digit LCD display using one of two
measuring modes: An automatic AC measurement mode or a manual DC
measurement mode. By limiting the test voltage of the Model 444-2 to only 100
micro volts the instrument will not "punch through" contamination or corrosion. An
audible tone can be used to indicate resistance values below any selected reading.
The Model 444-2 has a universal power input range of 85Vac to 250Vac and
incorporates a self-contained rechargeable Ni-Cad battery for field use.
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20,000 Count 4
1
/
2
-Digit LCD
2 Measurement Methods: AC Pulse and DC Polarity Switching
Punch-Through Prevention by 100 V Max. Test Voltage
User-Adjustable, Low-Resistance Alarm
AC Test Mode Cancels Offset Voltages and Thermocouple Effects
Includes Ni-Cad Battery for Field Use and Test Leads
Extended Battery Life, 10 Hours Typical
Specifications (Continued)
Relative Humidity:
90% maximum up to 35°C,
70% maximum up to +50°C (non-condensing)
Temperature Coefficient:
0.2%/°C (0° to 18°C and 28° to 50°C)
Extended Battery Life:
Typical 10 hours
Battery Mode Rated Circuit-To-Ground Voltage:
30V (RMS)
Display Settling Time:
<15 seconds
Dimensions:
2.7" x 8.4" x 9.0" (68 x 213 x 228 mm) nominal
Weight:
Approximately 3 Ibs.
Specifications
Range
20m
200m
2
20
Resolution
1
10
100
1m
Maximum Test Current
5mA
500 A
50 A
5 A
Accuracy:
(0.05% of input 600 counts) DC mode
(0.05% of input 15 counts) AC mode
Alarm:
Resistance below set point activates audible beeper and display annunciator.
Resistance above set point activates display annunciator.
Set point Adjustment:
Front Panel Knob
Accuracy:
(2% of input +150 counts)
Maximum Test Voltage:
100 V peak
Measurement Techniques:
(AC) Pulse of 50 Hertz Square Wave and DC Switchable
Polarity
Display:
19,999 count LCD with 0.5" digits and "AC," "DC," "B" and " " annunciators
Conversion rate:
reading 2 per second
Test Leads:
BNC to dual Kelvin clip (2 leads) RG-58
Operating Voltage:
85VAC to 250VAC , 10VA maximum
Operating Temperature Range:
0° to 50°C
Storage Temperature Range:
-40° to +60°C
Ordering Information
MICRO-OHMMETER
444-2 Micro-Ohmmeter, 85V/250V
Catalog No.
12681
ACCESSORIES
Standard Test Lead Set
Kelvin Test Probe Set
15
Catalog No.
00827
02151
ACCESSORIES
Case, Molded Plastic
Catalog No.
45029
电源技术
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