Description
Overview of Overload Shedding System
- The ASH-441H is equipped with overload shedding system to prevent main transformer overload trip and regional power outage, and pre-classify loads by priority for steady power supply.
- Equipped with Overload Shedding Device, it cuts off low-priority loads step by step during main transformer overload, ensuring stable transformer operation and continuous power supply to important loads.
Protection features
- Overload interlock protection;
- PT open circuit.
Communication Functions
- The device supports three communication modes: RS-485, CANBUS and Ethernet. Please specify the required mode when placing orders.
- It uploads real-time data including measured values, waveform recording data, fault signals, alarm signals, as well as all protection setting values, configurations and coefficients. Remote online modification of setting values and switching of protection functions are available.
- It receives commands from the master station, mainly including remote control, system time synchronization, setting parameter configuration, data reading and writing, etc.
Event Records & Fault Wave Recording
- Recorded events cover protection operation events and device self-check faults.
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It records the type, occurrence time and operating parameters during protection actions, as well as the type and occurrence time of device self-check faults.
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Fault wave recording contents include protection action time, action type and effective values before and after wave recording triggering.
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Fault wave recording data length: 2 cycles before fault and 4 cycles after fault for each channel, total 192 sampling points per channel.
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48 groups of SOE data and 16 groups of fault reports can be saved after power failure.
Monitoring Function
- The device can measure analog quantities such as current, voltage and frequency.
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Collect position signals of circuit breaker, energy storage device, isolating switch, remote/local mode and other digital signals.
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Support opening and closing control of circuit breakers.
Display Function
- Equipped with Chinese LCD display, status indicator lights and keyboard on the panel. It realizes real-time measurement monitoring, online setting modification and protection function switching. Fault indicator lights can be reset via local reset key or remote control.
Setting Table
| No. | Display Name | Range | Step | Remarks |
|---|---|---|---|---|
| 1 | Overload Alarm Setting | |||
| 1.1 | Alarm Delay | 0.00～120.00s | 0.01s | |
| 1.2 | Alarm Setting Value | 0.40～99.99A | 0.01A | |
| 1.3 | 1st Stage Overload Switch-in/Out | 1/0 | 1=Enable, 0=Disable | |
| 1.4 | 2nd Stage Overload Switch-in/Out | 1/0 | 1=Enable, 0=Disable | |
| 1.5 | 3rd Stage Overload Switch-in/Out | 1/0 | 1=Enable, 0=Disable | |
| 1.6 | 1st Stage Delay | 0.00～120.00s | 0.01s | |
| 1.7 | 2nd Stage Delay | 0.00～120.00s | 0.01s | Start timing when current exceeds inter-tripping setting after 1st stage action |
| 1.8 | 3rd Stage Delay | 0.00～120.00s | 0.01s | Start timing when current exceeds inter-tripping setting after 2nd stage action |
| 1.9 | Inter-tripping Setting Value | 0.40～99.99A | 0.01A | Overload inter-tripping value shall be greater than overload alarm value |
| 2 | General Setting | |||
| 2.1 | PT Broken Wire Detection | 1/0 | 1=Enable, 0=Disable | |
| 2.2 | 3-phase 4-wire Voltage Wiring | 1/0 | 1=3-phase 4-wire, 0=3-phase 3-wire | |
| 2.3 | 380V Measuring Voltage | 1/0 | 1=Secondary rated voltage 380V, 0=100V; Default:0 (100V) | |
| 2.4 | 1A Rated Current Mode | 1/0 | 1=Secondary rated current 5A, 0=1A; Default:0 (5A) |
Outline and Installation Dimensions of Automatic Load Shedding Device (ALS Device)
FAQ
Q：What is the difference between general load-shedding device, low-frequency and low-voltage load-shedding device as well as intertrip load shedding device?
A:Both belong to power system stability control devices yet differ greatly in practical application scenarios.
| Item | Under-frequency & Under-voltage Load Shedding Device | Intertrip Load Shedding Device |
|---|---|---|
| Defense Line Position | The third line of defense (final defense line) | The second line of defense (stability control device, supplement to relay protection) |
| Core Purpose | Prevent frequency and voltage collapse, avert widespread power outages | Eliminate overload and power imbalance, maintain balanced regional power generation and supply |
| Aliases | Automatic Frequency Load Shedding (AFL), Under-frequency Load Shedding, UFLS/UVLS | Intertrip unit, overload intertrip device, remote load shedding device |
Q：In what settings are overload shedding systems primarily used?
A:This Industrial Plant Overload Shedding System cuts down overloads to guarantee steady operation of industrial equipment, while Substation Stability Control and Load Shedding realizes rational load regulation and shedding to sustain power grid stability, and Microgrid Overload Protection Device applied in renewable energy microgrids keeps the balance between power generation and power consumption.
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