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Selection and protection of a motor
(2) Set two different electronic thermal O/L relays (Pr. 51)
Use this function when running two motors of different rated currents individually by a single inverter. (When running two
motors together, use external thermal relays.)
Set the rated current of the second motor to Pr. 51.
When the RT signal is ON, thermal protection is provided based on the Pr. 51 setting.
(3) Electronic thermal relay function prealarm (TH)
Pr. 450
Second applied
motor
Pr. 9
Electronic
thermal O/L relay
Pr.51
Second electronic
thermal O/L relay
RT = OFF RT = ON
First
motor
Second
motor
First
motor
Second
moto
r
9999 0
9999 ××××
0 ××××
0.01 to 500 ×Δ×
9999 Other than 0
9999 × ×
0 ×Δ×
0.01 to 500 ΔΔ
Other than 9999 0
9999 ××××
0 ××××
0.01 to 500 ×Δ×
Other than 9999 Other than 0
9999 ΔΔ
0 ×Δ×
0.01 to 500 ΔΔ
... Output current value is used to perform integration processing.
Δ.... Output current is assumed as 0A to perform integration processing. (cooling processing)
× .... Electronic thermal relay function is not activated.
REMARKS
The RT signal acts as the second function selection signal and makes the other second functions valid. (Refer to page 143)
100%: Electronic thermal O/L relay alarm operation value
The electronic thermal relay function prealarm (TH) is
displayed when the electronic thermal O/L relay
cumulative value reaches 85% of the level set in Pr. 9 or
Pr. 51. If it reaches 100% of the Pr. 9 Electronic thermal
O/L relay setting, a motor overload trip (E.THM/E.THT)
occurs.
Parameters referred to
Pr. 71 Applied motor Refer to page 125
Pr. 72 PWM frequency selection
Refer to page 163
Electronic thermal
relay function
operation level
Not
displayed
Not
displayed
Displayed
Displayed
100%
85%
Time
Electronic thermal
relay function
prealarm (TH)