Specifications

E - 4 Protections Ver: 0002
1.3 PERMANENT DUTY CYCLES ALLOWED TO THE DRIVE,
CALCULATING THE I2T PRODUCT.
Chapter EM indicates which is the maximum current allowed for permanent duty cycles (S1).
The higher the ambient temperature, the lower the capabilities of the drive. Thus, the operator
must decrease the demands in the duty cycles. This effect of the temperature is called "power
Derating".
The graphs below include two examples of Derating. The duty cycle S1 means a constant
load that brings the system to its maximum temperature.
The drive estimates the temperature of the IGBTs based on the rms current circulating
through them.
The following equation calculates the rms current:
This temperature estimate is based on the calculation we call I
2
t.
If this temperature exceeds a predetermined value, error 202 will be activated Drive
overload.
For a system with some particular IGBTs, the drive allows rms currents (estimated by
calculating the I
2
t) of:
for synchronous motors.
for asynchronous motors.
() ()
Irms i t d t
2
t
t
=⋅
+
∫
τ
Irms 0.5 I
IGBT
=⋅
Irms
I
2
IGBT
=
(thermal equilibrium)
Tmax
S1 DUTY CYCLE
according to the
IEC 34-1
Temperature Load
t
t
43
°C (°F)
Current
S1 (Amp)
35 (95)
53
55 (131)
SPD 2.75
AXD 3.100
45
°C (°F)
Current
S1 (Amp)
45 (113)
50
55 (131)