Basler BE1-851 Overcurrent Protection System: A Complete Guide to Professional Debugging and Troubleshooting

CT Ratio: The turns ratio (e.g. 800:5) needs to be entered.

Phase Rotation: ABC or ACB, incorrect settings can result in negative sequence measurement errors.

Save and Upload: Save the configured settings file (. bst file) and write it to the relay through "Upload Settings to Device".

Deep configuration of core functions

4.1 Overcurrent protection (50/51)

This is the core function of BE1-851, which has extremely high flexibility.

Fixed time overcurrent (50T): 6 independent components (50TP, 50TN, 50TQ, 150TP, 150TN, 150TQ). The settings include "Pickup value" and "Time Delay". Setting the time delay to 0 is a purely instantaneous action.

Inverse time overcurrent (51): Suitable for situations that require coordination with downstream equipment. BE1-851 provides over 16 standard inverse time curves, compatible with ABB CO series, GE IAC series, and IEC/BS standards.

Negative sequence overcurrent (50TQ/51Q): an extremely practical function. Negative sequence overcurrent protection is more sensitive to phase to phase faults. The typical setting is half of the starting value for phase overcurrent to achieve equal sensitivity to phase faults and three-phase faults.

Operation guide: In the "51" tab of the "Overcurrent" screen, select "Curve" such as "I1" (similar to ABB CO-8), and set the "Time Dial". To use the integrated reset feature (analog induction disk reset), add "R" after the curve name (such as S1R).

4.2 BEST Logic Programmable Logic (Core Value)

BEST logic is the soul of BE1-851, which implements the "soft wiring" between the internal components, inputs, and outputs of the relay through logical equations.

Logical variables: including inputs (IN1-IN4), protection element outputs (such as 51PT=51P trip), and virtual outputs (VO1-VO15).

Logical equation: For example, to make OUT1 (hardware output 1) act when 51P trips or 101T (virtual circuit breaker control switch trips), the logical expression is: SL-VO1=51PT+101T.

Pre programming scheme: For engineers who are not familiar with logic programming, BE1-851 comes pre programmed with various schemes, such as Feeder_1 (basic overcurrent+circuit breaker failure), Feeder_2/3/4 (with reclosing function), and BUS/ACKUP (bus protection coordination scheme). You can directly copy and use it in the "BEST logic">"Logic Select" tab of BESTCOMS.

Advanced features and application skills

5.1 Setting Groups

BE1-851 supports 4 sets of set values (SG0-SG3) to cope with different system operation modes (such as cold load start-up, maintenance of a transformer, etc.).

Automatic switching: A monitoring element (such as 51P) can be set to automatically switch to another set of settings when the current exceeds the "Switch Threshold" and lasts for a period of time, and return when the current drops back.

Logical switching: It can be forced to switch to a specified group through external input (such as IN2) or logical expression.

5.2 Circuit Breaker Failure Protection (BF)

Function: When the protection issues a trip command and the circuit breaker fails to disconnect the fault current within the set time, it outputs a malfunction trip signal (BFT) to trip adjacent circuit breakers.

Fast Dropout Detector: Unlike ordinary current measurement, this algorithm directly analyzes the current sampling point and can determine whether the current is cut off within less than one cycle, greatly improving the speed of failure protection.

5.3 Fault recording and analysis

BE1-851 supports fault recording in COMTRADE format.

Trigger: Defined by the SG-TRIGGER command. TRIP trigger, PU trigger, and LOGIC trigger need to be set.

Type H vs. G: The number of recorded waves supported varies depending on the hardware version. For example, version 3. xx supports 16 wave recordings, with 15 cycles per recording and 24 sampling points per cycle.

Operation guide: In the "Reporting and Alarms">"Fault Recording" tab, click the "Logic" button to add the output of the protection element that needs to trigger the recording (such as 51PT) to the TRIPPED or PICKED UP logic expression.

Frequently Asked Questions (FAQ)

6.1 "Trip LED unable to reset? ”

Answer: The "Reset" button of BE1-851 is context sensitive. The 'reset' button can only clear the trip LED and lock the target when in the 'Target' screen; When in the 'Alarm' screen, it is used to reset the alarm.

I have set the startup value and time, but the function is not working

Answer: Please check the BEST logic settings. Even if the setting value of the protective component is correct, if the component is not enabled in BEST logic (Mode=Enabled) or its Block input is set to logic 1, the component will not act.

Why can't I modify settings through serial port

Answer: In ASCII command mode of BE1-851, before modifying any settings, you must first use the ACCESS=password command to obtain write permission. At the same time, access to the three communication ports (COM0 front, COM1 rear, COM2 RS-485) is mutually exclusive, and only one port can have write permission at a time.