The electric control system of the escalator realizes the operation control of the escalator, and is mainly composed of control rejection, control buttons, various switches and control loops. The electrical control methods of the escalator include relay control, programmable control, microcomputer control, pole-changing and variable-voltage inverter control. The main features of the escalator electrical control system are as follows:
(1) The escalator is basically started without loading;
(2) The running speed of the escalator remains unchanged;
(3) The escalator does not brake frequently;
(4) The escalator does not need to change the running direction during normal operation;
(5) The escalator does not have to consider the operating position and operating status.
The main circuit of the escalator, the power supply loop of the brake should be interrupted by at least two sets of independent electrical devices to ensure that any one of the electrical devices is not disconnected after the escalator is stopped, and the escalator cannot be restarted. Figure 5-15 and Figure 5-16 show the schematic diagram of the relay control system of the escalator.
1. The main circuit
By air circuit breaker QFl, phase sequence relay KP, thermal relay FRl. Main contact points of upper and lower contactors KMl, KM2, and main contact points KM3, KM4 of "star-delta" change contactor, drag motor M1, brake motor M2 (or power-off brake YB), lubrication motor M3 .
The circuit completes the functions of starting, automatic, stopping, and "star-delta" conversion, ascending, descending, and lubricating under the action of the control circuit. Simultaneous short circuit, leakage, phase error, open circuit, over current protection
2. Control circuit
When the control circuit is in operation, it is controlled by the start and stop buttons sA3, SA4 and the three position switches STP1 and STP2 respectively arranged on the upper and lower parts of the escalator to control the up and down movement and stop of the escalator. When the three position switch SA3 is rotated to the up position, KA3 is turned on and self-locking, and the KA4 power supply is turned off. The upstream contactor KM1 is turned on, the escalator is used for upward movement, and the KM2 power supply is cut off to realize uplink and downlink electrical interlocking. When the three position switch sA3 is turned to the down position. The KA4 is turned on and self-locking while disconnecting the KA3 power supply. The downstream contactor KM2 is turned on, the escalator is used for downward movement, and the KMl power supply is cut off to realize the uplink and downlink electrical interlocking.
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