Chapter 1 -- Safety Considerations--Operation with Earth Grounded Cells and Auxiliary Apparatus
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An earth ground connection can cause problems when testing batteries, fuel cells, or capacitors. Many of these
devices can source huge currents, often 10’s or 100’s of amps. If the Reference 3000 chassis is earth grounded
and another location in the stack is accidentally (or intentionally) connected to earth ground, a portion of the
stack is shorted through the Reference 3000’s cell cable. Very large current flows when this occurs. Fuses in
the cell cable will open up to prevent damage to the instrument. When this happens, the failed fuses must be
replaced before the instrument can be used again. The fuses in the cell cable are not essential for operator
safety. A section in Chapter 5 describes the fuses and their replacement in detail.
NOTE
The fuses in the Reference 3000 cell cable do not protect against a safety hazard. They
are needed to prevent damage to the instrument if it is improperly connected.
Operation with Earth Grounded Cells and Auxiliary Apparatus
As described above, the Reference 3000 circuitry is isolated from earth ground, allowing it to make
measurements on cells that include an earth ground. This ground isolation is often called floating operation.
Cells with earth ground include many autoclaves, pipelines and storage tanks, and many fuel cell systems.
Connection of the Reference 3000 to auxiliary apparatus will often earth ground the Reference 3000,
destroying its ability to float and make measurements on earth grounded cells. Connection of the Monitor
BNCs to an oscilloscope is an example where the instrument is earthed.
The User I/O connector can be connected to earth grounded apparatus without earth grounding the Reference
3000, if the cabling is done carefully. The Metal Shell on the Reference 3000 User I/O Connector is
connected to the instrument's chassis which is a Floating ground. In a system that needs isolation from earth
ground, the shield of a User I/O cable must not connect the D-connector's metal shell to earth ground. All
User I/O signals should be referenced to pin 6 of the D-connector, which is isolated ground on the Reference
3000.
Caution
Floating operation of the Reference 3000 can be compromised by improper cabling to the
User I/O Connector. Do not use standard 15-pin shielded cables with this connector.
Custom cables with the shield connected to pin 6 of the D-connector are required.
WARNING
Do not connect the chassis ground binding post to any voltage other than earth ground.
An improper connection can create a safety hazard, which could result in personal injury
or death.
The Reference 3000 contains surge suppressors that limit the voltage difference between the Reference 3000’s
chassis ground and earth ground to about 40 volts. These surge suppressors are not part of the safety
mechanisms in the Reference 3000. Instead they are present to limit the possibility of improper instrument
operation or instrument damage due to electrostatic discharge (static electricity) and other surge events such as
lightening.
Temperature and Ventilation
Your Reference 3000 Potentiostat/Galvanostat/ZRA was designed for indoor use at ambient temperatures
between 0°C and 45°C.
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