Automation Direct DURApulse GS4 User Manual page 240

Chapter 4: AC Drive Parameters
P6.39~P6.44 PTC/RTD(PT100) Parameters
Parameters P6.39~P6.44 define how the drive protects the motor when either a PT100 RTD or a
PTC is used to monitor motor temperature. An analog output is used to supply current through
the temperature detecting device and an analog input is used to measure the voltage generated.
From the known excitation current and the measured voltage, the resistance of the device can be
calculated.
For an RTD, this resistance can be used to look up the corresponding temperature (PT100 has a
standard resistance/degree chart).
A PTC has a very abrupt change to its resistance/degree. PTCs are ordered based on the
temperature where this abrupt change occurs. Below the switching threshold, the PTC will
have very little resistance (could be ≈100Ω, depending on PTC). At the switching threshold, the
resistance increases dramatically (the resistance increases by ≈1MΩ over an ≈20°C increase in
temperature).
RTD(PTD100) vs. PTC Characteristics
• An RTD(PTD100) can give you fairly accurate feedback of the motor temperature�
• A PTC can only tell you if the motor temperature has passed the PTC's switching temperature (set
during PTC manufacturing)�
Examples of how to set up each type of sensor follow P6.44.
P6.39 PTC/RTD Detection Selection (Positive Temperature Coefficient)
Range/Units (Format: 16-bit binary)
0: Warn and continue operation
1: Fault and Ramp to Stop
2: Fault and Coast to Stop
3: No Warn
For PTC operation (analog input = #6, PTC Thermistor), this parameter defines the behavior of the
drive when the PTC thermistor on the motor gets too hot as defined by P6.40.
For PT100 RTD (P4.02, P4.03, or P4.04 Analog Input = #11 PT100 input), this parameter defines the
behavior of the drive when the RTD on the motor gets too hot as defined by P6.41 and P6.42.
Related parameters: P6.39~P6.44; refer to further information following P6.44.
P6.40 PTC Level
Range/Units (Format: 16-bit unsigned)
0�0~100�0%
This parameter sets the PTC trip level. The corresponding value for 100% is the maximum analog
input value. For most applications, a value of 50% will work.
The PTC will allow current to pass freely until the temperature reaches the PTC's switching point.
When the PTC resistance starts to change, it changes rapidly. A 70°C PTC may stay at ≈100Ω until
it reaches 70°C. At that point, the resistance will jump up to >1MΩ. (This will cause the analog
voltage input to jump well over the 50% default level set in P6.40).
• For PTC faults to work, PT Drop Freq (P6�43) must be = 0�
• One of the analog input functions (P4�02~P4�04) needs to be set to 6 (PTC thermistor input value)�
• P6�40 must be >0�
Related parameters: P6.39~P6.44; refer to further information following P6.44.
Page 4–146
AO2 AI1 ACM
PT100
+ –
DURA
GS4 AC Drive User Manual – 1st Ed, Rev A - 10/20/2017
pulse
Type Hex Addr Dec Addr
♦R/W 0627 41576
Default
0
Type Hex Addr Dec Addr
♦R/W 0628 41577
Default
50�0