1. product introduction
The SW-DLZ300 phase-to-ground short circuit (zero sequence) protection device (guide rail type) developed for electrical engineering is suitable for different site requirements, and has the characteristics of space saving, convenient and quick installation, convenient operation and maintenance, etc. The open type intelligent zero sequence transformer is fixed on the drawer mounting plate without changing the primary line, thus reducing the amount of renovation work. The phase-to-ground short circuit protection outlet drives the shunt coil (shunt trip) of the molded case circuit breaker to trip to realize the phase-to-ground short circuit (zero sequence) protection function. At the same time, the alarm contact outputs a yellow light alarm to prompt the drawer to exit operation due to zero sequence protection action, and adjust the setting value (current threshold and delay) of phase-to-ground short circuit protection.

The SW-DLZ300 phase-to-ground short-circuit monitoring and protection device is used in combination with a display host (optional), a single phase-to-ground short-circuit protection device and a high-precision zero-sequence current transformer. One display host and multiple single phase-to-ground short-circuit monitoring and protection devices are installed in each low-voltage cabinet to manage multiple outgoing circuits. The display host group is responsible for parameter setting and local display, and RS485 communication mode is used for numerical setting and data display with multiple single-channel short-circuit monitoring and protection devices; the single-channel phase ground short circuit monitoring and protection device is responsible for collecting zero sequence current, zero sequence current calculation, zero sequence current primary and secondary isolation conversion, fixed value setting (parameter setting and fixed value setting can be performed by computer software when there is no display host), protection logic judgment control, trip control outlet and other functions, and has independent communication function with the upper computer, and can be flexibly configured according to the site conditions.

2. features:
Strong anti-interference ability: zero sequence current measurement circuit is isolated by two-stage current transformer;
High measurement accuracy: the device provides voltage acquisition function, regardless of the line zero sequence current under any circumstances, can follow the grid frequency real-time sampling calculation, to ensure measurement accuracy;
Real-time monitoring and protection: real-time monitoring of the zero sequence current of each outgoing line, timely warning, timely output of trip signal, to avoid the accident expansion;
Flexible installation method: the device is small in size and convenient to install; The SW-DLZ300 device body is very small and can be installed in a drawer or at the back of a low-voltage cabinet in a guide rail type, which is especially conducive to on-site modification and installation. The installation of the device will definitely not affect the safe operation of the main components;
Early warning trip function: supports two-level early warning. When the system detects that the grounding current exceeds the early warning set value, it will give an alarm and automatically delay and adjust to the lower-level set value until the trip cuts off the faulty line or motor. The corresponding third-level tripping action time and tripping setting value can be set according to the on-site working conditions to avoid the starting unbalanced current and cooperate with the higher-level zero sequence protection to prevent large-level power failure caused by leapfrog tripping. You can also choose to only alarm without tripping;
The high-precision zero-sequence current transformer adopts the automatic compensation design of "ultra-micro crystal iron core" and "zero magnetic flux technology", so that the transformer is always in an ideal "zero magnetic flux" working state, which improves the sensitivity of the transformer and reduces the external dimensions of the transformer;
The man-machine interface is friendly, the fixed value is unified management, the operation is simple, the alarm information is intuitive, and it is convenient for on-site setting and inquiry.

3. technical parameters:
Working power supply: AC/DC220V 20%;
Working environment: temperature:-25 ℃ ~ 55 ℃, relative humidity: ≤ 95%;
Use voltage level: 0.4kV;
The monitoring circuit: the SW-DLZ300 type is 1 way;
Input current: 3 ~ 120mA;
Sampling accuracy: ± 0.1A;
Alarm trip: capacity DC250V, 1A, normally open contact;
Earthing warning: 3 ~ 100A (settable);
Grounding trip: 5 ~ 100A (refundable and settable);
Data transmission: RS485 bus, standard MODBUS communication protocol;
The installation method: SW-DLZ300 rail type installation;
Historical records: 100 records can be stored and will not be lost after power failure.