Mitsubishi Electric 800 Series Instruction Manual page 320

Set two types of electronic thermal O/L relays (Pr.51)
MC
MC
U
V
W
RT
SD
• These settings are used when rotating two motors with different rated current separately by a single inverter. (When rotating
two motors together, use an external thermal relay.)
• Set the rated motor current for the second motor in Pr.51.
• When the RT signal is ON, thermal protection is provided based on the Pr.51 setting.
Pr.450
Second applied Electronic
motor thermal O/L relay
9999 0
9999 Other than 0
Other than 9999 0
Other than 9999 Other than 0
: Values are accumulated by using the output current.
∆: Values are accumulated by assuming the output current is "0 A" (cooling processing).
: Electronic thermal O/L relay does not operate.
NOTE
• The RT signal is a second function selection signal. The RT signal also enables other second functions. (Refer to
• The RT signal is assigned to the terminal RT in the initial setting. Set "3" in any of Pr.178 to Pr.189 (Input terminal function
selection), to assign the RT signal to another terminal.
Motor permissible load level setting (Pr.607, Pr.608)
The electronic thermal O/L relay operation characteristic can be changed by setting the permissible load level according to the
motor characteristics.
Motor permissible
load 110%
240
180
120
60
0
80 100 120
Inverter output power (%)
(% to the inverter rated current)
Example of motor permissible load setting
(when Pr.9="100% of the inverter rating")
IM
IM
Pr.9 Pr.51
Second electronic
thermal O/L relay
9999
0
0.01 to 500 (0.1 to 3600)
9999
0
0.01 to 500 (0.1 to 3600)
9999
0
0.01 to 500 (0.1 to 3600)
9999
0
0.01 to 500 (0.1 to 3600)
Motor permissible
load 150% (Initial value)
Motor permissible
load 200%
Range for
the transistor
protection
140 160 180 200
(H) Protective function parameter
RT-OFF RT-ON
No.1 No.2 No.1 No.2
Motor Motor motor motor
   
   
 
∆

 
 
 
 ∆
 ∆ ∆ 
   
   
 
∆

 ∆ ∆ 
 
 ∆
 ∆ ∆ 
PARAMETERS
page 419.)
5
GROUP
H
319