
24
Epsilon Eb and EN Drives Reference Manual
the actual drive loading and ambient temperature.
The heat sink is designed with a certain amount of dissipation capability and the sum of
the heat generated by the drive bridge rectifier, power module and shunt resistor must be
less than this total capacity. For example, if the drive is operating near its continuous
current limit with a 40 ° C ambient, most of the heatsink capacity will be used to dissipate
the heat generated by the output power module and bridge rectifier. In this case the
allowable shunt power will be very low because the capacity is limited by the design.
Conversely, if the drive loading is very low and/or the ambient temperature is reduced,
the capacity to dissipate shunt power is increased. The relationship between the Shunt
dissipation capacity, Heatsink RMS loading and Ambient Temperature is shown in the
following charts.
Heatsink RMS
EN Only
EN
This parameter is available using the PowerTools FM Watch Window as a diagnostic tool.
It displays the effective Heatsink utilization based on the power dissipated by the input
bridge rectifier and the output power stage. The value of 100 percent is the maximum
continuous power dissipation available at 40 ° C ambient temperature with zero shunt
activity. The relationship between the Shunt dissipation capacity, Heatsink RMS loading
and Ambient Temperature is shown in the following charts.
Drive Ambient Temperature
EN Only
EN
The Drive Ambient Temperature parameter is located on the PowerTools FM "Advanced"
tab in the Detailed Setup View. This tab is not normally visible and it is only rarely
necessary.
The Drive Ambient Temperature is a parameter which will let the drive know the air
temperature around the drive heat sink while the system is under normal operating
conditions. If the actual ambient temperature is higher than 40 ° C, setting the Drive
Ambient Temperature parameter to the actual temperature will help to protect the drive
by activating the Shunt Fault at an appropriate time.
The Drive Ambient Temperature parameter determines the total amount of heat the heat
sink can dissipate. Each Watt of power dissipated will produce an incremental rise in
temperature. So, if the ambient temperature is lower, more wattage can be dissipated
before reaching the temperature limit of the components mounted to the heatsink.
By default, we assume an ambient temperature of 40 ° C which is the design ambient
temperature for the nominal maximum drive current. If the actual ambient is lower than
this, extra capacity is available for additional shunt power dissipation. Setting the Drive
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