In waste heat power generation, low voltage drawer cabinet room voltage below 660V, current below 1000A control and cabinet electrical equipment. It is the middle link of automatic control, and it is an important link connecting DCS cabinet and field actuator. Its reliable operation is an important part of power plant to improve power generation and create high income. We need to understand its principle, operation method and matters needing attention during maintenance and operation.

一、抽屉柜按作用来分可分为馈电型柜及控制型柜

1、 Drawer cabinet can be divided into feed cabinet and control cabinet according to its function

1、馈电型柜

1. Feeder cabinet

它的主要功能就是将低压母线的三相电压通过柜内的断路器往变频器控制柜软启柜、站用控制屏等电气柜供电，抽屉柜的空开具有脱扣跳闸线圈，起到保护送电线路及终端设备短路保护，切换故障电源作用，它通过主电路上串接电流互感器及配备电流继电器，当检测到短路电流时就使具有反时限的电流继电器动作，驱动柜内主电路断路器脱扣线圈，切换故障电源，短路电流越大，动作时间越短，这是反时限保护的一大特点。大电流馈电柜中，基本都装有这种保护设备，供电电流较小的时候，可依靠断路器本身的保护动作即可。

Its main function is to supply the three-phase voltage of the low-voltage bus through the circuit breaker in the cabinet to the soft start cabinet of the inverter control cabinet, the station control panel and other electrical cabinets. The air switch of the drawer cabinet has a trip coil, which can protect the short-circuit protection of the transmission line and terminal equipment, and switch the fault power supply. It is connected in series with the current transformer and equipped with the current relay through the main circuit, When the short-circuit current is detected, the current relay with inverse time limit will act to drive the trip coil of the main circuit breaker in the cabinet and switch the fault power supply. The larger the short-circuit current is, the shorter the action time is. This is a major feature of inverse time limit protection. When the power supply current is small, the protection action of the circuit breaker itself can be relied on.

2、控制型柜

2. Control cabinet

其主要作用就是通过断路器及接触器，继电器设备组合控制电路，将中 央控制室DCS控制信号，实施对拉链机、关断阀、凝结水泵等电气设备的正反转及抽屉柜上电机综合保护，当电机缺相或短路堵料负荷重时，保护器常开触点闭合切断抽屉柜的控制回路，控制接触器短电，切断电源。控制柜还有继电器与控制电路乙炔，中控电脑与设备通讯正常。

Its main function is to implement the forward and reverse rotation of zipper machine, shut-off valve, condensate pump and other electrical equipment and the comprehensive protection of the motor on the drawer cabinet through the DCS control signal of the central control room through the combined control circuit of circuit breaker, contactor and relay equipment. When the motor is lack of phase or short circuit, the normally open contact of the protector will close and cut off the control circuit of the drawer cabinet, Control contactor short circuit, cut off the power supply. The control cabinet also has relay and control circuit, and the communication between central control computer and equipment is normal.

二、低压抽屉柜注意事项

2、 Precautions for low voltage drawer cabinet

抽屉柜一般禁止主电路负责带电推进，直接带负荷，所以低压抽屉柜均带机械连锁机构。

Drawer cabinet generally forbids the main circuit to be responsible for live propulsion and directly load, so low-voltage drawer cabinets are equipped with mechanical interlocking mechanism.

1、推进时，首先要对准导轨，平衡推进（控制柜位置开关处于断开位置，闭锁小开关处于进出位置）。

1. When pushing, first of all, it is necessary to aim at the guide rail and balance the pushing (the position switch of the control cabinet is in the off position and the locking small switch is in the in and out position).

2、闭锁小开关位置介绍：

2. Introduction to the position of locking small switch:

a、运行位置

a. Operating position

b、试验位置

b. Test location

c、进出位置

c. In and out position

d、检修位置

d. Maintenance position

3、抽屉柜操作时，一定要查看好闭锁小开关位置在操作，不要盲目操作，以免造成设备故障。

3. When operating the drawer cabinet, it is necessary to check the position of the small locking switch, and do not operate blindly, so as not to cause equipment failure.