Mitsubishi Electric FR-A720-00030-NA Instruction Manual page 234

(4) Protective functions
If any of the following errors occurs in the brake sequence mode, the inverter results in a fault, trips, and turns OFF the
brake opening request signal (BOF).
Fault Display
(Detection frequency) - (output frequency) > Pr. 285 during encoder feedback control
E.MB1
When Pr. 285 Overspeed detection frequency = 9999, overspeed is not detected.
Deceleration is not normal during deceleration operation from the set frequency to the frequency set in
E.MB2
Pr. 282. (when Pr. 284 =1) (except stall prevention operation)
E.MB3 Brake opening request signal (BOF) turned ON though the motor is at a stop. (gravity drop prevention function)
Although more than 2s have elapsed after the start command (forward or reverse rotation) is input, the brake
E.MB4
opening request signal (BOF) does not turn ON.
Although more than 2s have elapsed after the brake opening request signal (BOF) turned ON, the brake opening
E.MB5
completion signal (BRI) does not turn ON.
Though the inverter had turned ON the brake opening request signal (BOF), the brake opening completion signal
E.MB6
(BRI) turned OFF midway.
Although more than 2s have elapsed after the brake opening request signal (BOF) turned OFF at a stop, the
E.MB7
brake opening completion signal (BRI) does not turn OFF.
CAUTION
 During deceleration, inverter output is shut OFF when the frequency reaches Pr.13 Starting frequency or 0.5Hz, whichever is lower.
For Pr. 278 Brake opening frequency, set Pr. 13 or a frequency equal to or higher than 0.5Hz.
 Overspeed detection (Pr. 285) is valid under encoder feedback control (used with the FR-A7AP/FR-A7AL (option) even if a value
other than "7 or 8" is set in Pr. 292.
 Setting Pr. 278 Brake opening frequency too high activates the stall prevention and may cause E.MB4.
 If the sum of the time between Pr. 13 Starting frequency and Pr. 278
Brake opening frequency + Pr. 280 Brake opening current detection time
is more than 2s, E.MB4 occurs.
Parameters referred to 
Pr. 80 Motor capacity, Pr. 81 Number of motor poles
Pr. 180 to Pr. 186 (input terminal function selection)
Pr. 190 to Pr. 195 (output terminal function selection)
Pr. 800 Control method selection
Encoder feedback control Refer to page 389
Refer to page 91
Refer to page 235
Refer to page 243
Refer to page 91
Motor brake and stop operation
Description
Pr. 278
Pr. 13
Brake opening request
(BOF signal)
Less than 2s
Output
frequency
(Hz)
Pr. 280
Time
ON
223
4