Rockwell Automation 20D PowerFlex 700S with Phase I Control Reference Manual - Manual (Page 23)

Rockwell Automation Publication PFLEX-RM002D-EN-E - August 2013 23
Detail Drive Configuration and Operation Chapter 1
Watts) with typical values in the range of 30 to 100 times higher than the
resistor’s continuous power rating.
Parameter 416 [Brake Pulse Watts] = (Resistors peak energy in Joules)/1 second;
where the resistor package’s peak energy rating is obtained from the resistor
manufacturer.
When the resistor package’s peak energy rating cannot be obtained, there are a
few other ways to approximate parameter 416 [Brake Pulse Watts]:
[Brake Pulse Watts] = 75,000 (watts/lb) x Resistor element weight (lb); where
75,000 represents a specific heat of 0.11 cal/Kg °C (steel or nichrome) and a
temperature rise of 350 °C, and the resistor element weight is the total weight of
the resistor wire element in pounds (not the entire weight of the resistor cage).
For example a resistor with a nichrome element that weights 10 lb would have:
[Brake Pulse Watts] = (Time Constant) x parameter 417 [Brake Watts]; where
the Time constant equals the amount of time for the resistor to reach 63% of its
rated temperature with applied rated watts (parameter 417 [Brake Watts]).
Parameter 417 [Brake Watts] sets the continuous watts for determining the
protection for an external brake. Enter the continuous watt rating of the resistor
cage (found on the resistor cage nameplate or from the resistor manufacturer) for
this parameter. This parameter is active only if the configuration is selected for an
external brake ([Bus/Brake Cnfg] bit 1 set to 1). When the internal brake resistor
is used then the protection is determined from the drive-internal values.
Parameter 369 [Brake OL Cnfg] determines how the drive reacts when the brake
protection is exceeded. Regardless of the parameter 369 [Brake OL Cnfg]
setting, the drive does not command the 7th IGBT to switch when the brake
resistor protection is exceeded. Some possible settings for this parameter are:
Parameter 369 [Brake OL Cnfg]
Setting Drive Operation
0 - “Ignore” The drive does not generate the fault 38 “Brake OL Trip” or alarm “Brake OL Trip.”
1 - “Alarm” The drive generates an alarm “Brake OL Trip,” but does not generate the fault 38
“Brake OL Trip.”
2 - “FltCoastStop” The drive generates the fault 38 “Brake OL Trip” and issues a coast stop.
3 - “FltRampStop” The drive generates the fault 38 “Brake OL Trip” and issues a ramp stop.
4 - “FltCurLimStop” The drive generates the fault 38 “Brake OL Trip” and issues a current limit stop.
Parameter 416 [Brake Pulse Watts] 75,000 10
×
750,000 Watts = =