5
The 3M
™
Wrist Strap Monitor Model 725 requires only a small amount of current to operate.
When the red lamp and the audible alarm are activated simultaneously, the monitor requires
approximately 5 μA of current. When the lamp and alarm are not activated (normal condition),
the monitor requires approximately 50 μA of current.
As with any battery operated electronic device, the life
of the battery will be determined by the frequency of
use. However, for the Wrist Strap Monitor Model 725
you can expect a battery life of approximately one year
in continuous operation under normal conditions.
Note: Use an alkaline battery for longer life.
The Wrist Strap Monitor Model 725 monitors
the battery voltage and alerts the operator when it is necessary to change the
battery. When the battery voltage falls below 6 volts the red lamp will illuminate
with no audible alarm. At this time the Wrist Strap Monitor Model 725 is still
operational, making reliable resistance measurements of the wrist strap assembly
and the ground connection.
Voltage on Operator when Connected to the 3M Wrist Strap Monitor
Model 725
There is a concern about the voltage that is applied to an operator while they are connected
to a monitor. Some of today’s electronic components are extremely sensitive to electrostatic
discharge from a person (less than 10 volts). The following chart for the Wrist Strap Monitor
Model 725 illustrates the level of voltage that will appear on the operator under various
resistance conditions.
Voltage on Operator when connected to the Wrist Strap Monitor Model 725
Condition
Observed Voltage
No Skin Resistance
0.8V
200K Ohm Skin Resistance
0.9V
Likely Case Before Alarm
3.5V
Worst Case Before Alarm
6.8V
Absolute Worst Case
9.0V
NOTICE
The 3M
™
Wrist Strap Monitor
Model 725 does not have the
capability of verifying that the
ground point is a suitable ground.
If you are not sure what a suitable
ground is, contact a licensed
electrician before installation.
Note: For more information about wrist strap monitoring see Additional Wrist Strap Monitoring
Information (Section 12).
