Parker EY Series - Thermal Protection; Alarm Tripping with PTC Thermistors

49 – Pvd3675_Gb_Ey_Septembre_2017
3.7. Thermal Protection
Different protections against thermal overloading of the motor are proposed:
Thermoswitches (as an option), PTC thermistors (as standard) or KTY temperature (as
an option) built into the stator winding. The thermal sensors, due to their thermal inertia,
are unable to follow very fast winding temperature variations. They acheive their thermal
steady state after a few minutes.
Warning:
To protect correctly the motor against very fast overload,
please refer to §3.1.6. Peak current limitations
3.7.1. Alarm tripping with PTC thermistors
Once thermal probe (PTC thermistors) fitted in the EY servomotor winding, trips the
electronic system at 150°
±
5° C for class F version. When the rated tripping temperature
is reached, the PTC thermistor undergoes a step change in resistance. This means that
a limit can be easily and reliably detected by the drive.
The graph and tab below show PTC sensor resistance as a function of temperature (T
N
is nominal temperature)
Temperature
Resistance value for
EY6 andEY8
Resistance value for
EY3 andEY4
from -20°C to T
N
-20°C
R1≤500 Ω
R1≤750 Ω
from T
N
-20°C to T
N
-5°C
R2≤1100 Ω
R2≤1650 Ω
from T
N
+5°C to T
N
+15°C
R3≥2660 Ω
R3≥3990 Ω
greater than T
N
+15°C
R4≥8000 Ω
R4≥12000 Ω
R4
Resistance (Ω)
R3
R2
R1
T
N
-20°C
T
N
-5°C
T
N
+5°C
T
N
+15°C
Temperature (°C)
-20°C