Hitachi SJ300-037HFE 사용자 설명서

SJ300 Inverter

Oper

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ons

and Monitor

ing

The External Brake Control function enables the inverter to control external electromechanical 
brake systems with a particular safety characteristic. For example, elevator control systems 
maintain the brake on the load until the drive motor has reached a releasing frequency (point at 
which the external mechanical brake is released). This ensures that the load does not have an 
opportunity to begin coasting before the inverter begins driving the motor. The External Brake 
Control function can be enabled by setting parameter B120=01. The diagram below shows the 
signals that are important to this function.

The steps below describe the timing diagram of events on the following page.

1. When the Run command turns ON, the inverter begins to operate and accelerate to releasing 

frequency (B125).

2. After the output frequency arrives at the set releasing frequency (B125), the inverter waits 

for the brake release confirmation, set by B121. The inverter outputs the braking release 
signal [BRK]. However, if the output current of the inverter is less than the releasing current 
set by B126, the inverter does not turn ON the brake release output [BRK]. The lack of the 
proper current level indicates a fault (such as open wire to motor). In this case, the inverter 
trips and outputs the braking error signal [BER]. This signal is useful to engage an 
emergency brake to ensure the load does not move, if the primary braking system has failed.

3. While the brake release output [BRK] is ON, the inverter drives the motor but does not 

accelerate immediately. The inverter waits for confirmation from the external brake. When 
the external brake system properly releases, it signals the inverter by using the Brake OK 
input terminal [BOK].

4. When the brake operates properly and signals with the [BOK] input, the inverter waits for 

the required time for acceleration (B122), and then begins to accelerate to the set target 
frequency.

5. When the Run command turns OFF, the procedure outlined above happens in reverse. The 

idea is to engage the brake before the motor comes completely to a stop. The inverter decel-
erates to the releasing frequency (B125) and turns the brake release output [BRK] OFF to 
engage the brake.

6. The inverter does not decelerate further during just the waiting time for brake confirmation 

(B121). If the brake confirmation signal does not turn OFF within the waiting time for brake 
confirmation, the inverter causes a trip alarm and outputs the brake error signal [BER] 
(useful for engaging an emergency brake system).

7. Normally, the brake confirmation signal [BOK] turns OFF, and the inverter waits the 

required waiting time. Then the inverter begins to decelerate again and brings motor and 
load to a complete stop (see timing diagram on next page).

[BRK] Brake release

[BOK] Brake confirmation

[BER] Brake error

B120

Brake control 
enable

00=Disable

01=Enable

Enables external brake control function within the 
inverter

B121

Brake waiting 
time for release

0.00 to 5.00 sec.

Sets the time delay after arrival at release 
frequency (B125) before the inverter outputs brake 
release signal [BRK]

B122

Brake wait time 
for acceleration

0.00 to 5.00 sec.

Sets time delay after brake confirmation signal 
[BOK] is received until the inverter begins to accel-
erate to the set frequency