354 / 360
2015 Power Transmission Products
General Information
173
Under certain operating conditions, a belt drive may generate
static electricity. This poses a risk with belt drives used in the
presence of potentially explosive gases, liquids, powders,
dusts, etc., where the possibility of static sparks must be kept
to a minimum. Static discharge can also interfere with
sensitive electronic circuitry, radios and controls. Belts can be
manufactured with materials that facilitate a grounding path
for static electricity. It is common in the industry to refer to
such belts as “static conductive.” It is important to note that all
components of the drive must be conductive to establish
a clear grounding path to dissipate any static charge.
For non-synchronous (friction drive) power transmission
belting, Continental ContiTech references International
Standards Organization standard ISO-1813, which describes
a test procedure and fixture where electrodes are machined
to match the specific belt cross section profile. The maximum
allowable resistance, measured with an applied potential of
500 volts, is calculated from the formula shown below and
tabulated in the standard.
For synchronous power transmission belting, the reference
document is ISO standard 9563, which describes a test
procedure and fixture specific to synchronous belting, where
the electrodes are machined to match the specific tooth
profile of the belt. The maximum allowable resistance,
measured with an applied potential of 500 volts, is calculated
as follows:
R =
resistance in ohms
Where
L =
distance between electrodes
w =
width of the belt
Drive conditions and service variables in combination with
time in operation can result in a loss of static conductivity. It is
recommended that a conductivity check be added to drive
preventative maintenance programs where belt static
conductivity is a requirement.
Static Conductive Belts
R =
6x10 L
w
5
General Information
Automotive & Truck
Specialty
Bushing Hardware
V-Belt
Banded
Synchronous
Overview