Basler BE1-51 Time Overcurrent Relay Debugging Guide

Basler BE1-51 Time Overcurrent Relay: A Complete Guide to Principles, Testing, and Field Applications

Equipment Overview and Functional Positioning

The BE1-51 time overcurrent relay launched by Basler Electric is a digital protection relay designed based on a microprocessor, specifically designed for overcurrent protection in 50Hz or 60Hz power systems. This relay can monitor the AC current of single-phase, two-phase with neutral wire, or three-phase with neutral wire, providing accurate time overcurrent and instantaneous overcurrent protection functions. BE1-51 adopts a pull-out chassis structure and is installed in a standard power cabinet. It supports two installation methods: semi embedded or protruding, and can be matched with a test plug (Basler Electric part number 10095) to achieve on-site testing without disconnecting wires.

Compared with traditional electromagnetic overcurrent relays, the core advantage of BE1-51 lies in its highly flexible timing characteristic selection - by selecting different timing options (Z1, Z2, Z3), users can obtain up to 69 different overcurrent characteristic curves, covering inverse time limit, I ² t, BS142 standard curve, and integrated algorithm curve, greatly expanding the adaptability of relays.

Core technical specifications

2.1 Inductive input and measurement accuracy

BE1-51 provides multiple sensing input ranges, and continuously adjustable overcurrent start value settings are achieved through panel TAP selection switches and TAP CAL calibration potentiometers

5A CT input: low range 0.5~4.0A, high range 1.5~12.0A

1A CT input: low range 0.1~0.8A, high range 0.3~2.4A

The three-phase neutral wire model can also be combined with different ranges (such as high phase current range and low neutral wire range) to adapt to diverse on-site CT configurations. The time overcurrent startup accuracy is ± 2% of the set value. When the TAP CAL potentiometer is turned clockwise to its maximum, the actual startup value is within ± 5% of the panel TAP gear value. Exit ratio is better than 92% of the startup value. The starting value of the instantaneous overcurrent component can be continuously adjusted between 1-40 times the overcurrent starting value, with an accuracy of ± 2% and an exit ratio better than 98%.

2.2 Output contacts and target indication

The rated values of the output contacts are as follows:

Resistive load: capable of connecting/disconnecting/continuous current of 7A at 120Vac; capable of connecting 30A (0.2s), continuous current of 7A, and disconnecting 0.3A at 250Vdc

Inductive load (L/R=0.04): capable of breaking 0.3A at 120Vac, 125Vdc, and 250Vdc

The target indicator can be selected as internal excitation type or current excitation type (with at least 0.2A current flowing through the output circuit). The current excitation type target has been upgraded from an electromagnetic flipping indicator to an electronic latch LED indicator in products after August 2007, with power-off memory recovery function - after the power supply is interrupted, the previously latched target state will automatically recover after the power supply is restored, greatly improving the convenience of fault tracing.

2.3 Power Supply and Electromagnetic Compatibility

BE1-51 offers five power options, covering a wide range of inputs from 12~280Vdc and 90~270Vac, suitable for DC or AC power supply conditions in different power stations around the world. The power supply adopts an electrical isolation design with no polarity requirements. In terms of electromagnetic compatibility, the relay has passed the surge withstand capability (SWC) test of ANSI/IEEE C37.90.1-1989 and meets the dielectric withstand voltage requirements of IEC 255-5 and ANSI/IEEE C37.90 (all circuits to ground 2121VDC, input to output 1500Vac or 2121VDC).

Control panel and operating components

The front panel of BE1-51 integrates all operational control and status indicator components (see manual Figure 2-1):

TAP selector (A~J, 10 bit BCD dip code): Select the reference value for starting phase overcurrent

TAP CAL potentiometer (single turn): finely adjust the startup threshold between the selected TAP gear and the next gear

TIME DIAL selector (00~99): Set the multiple for over casting

INST 1/INST 2 control (four turn potentiometer): Set the action threshold of the first/second instantaneous overcurrent component separately (1-40 times the TAP value)

Target indicator (LED): Phase/neutral line component target, timing function target, instantaneous 1/2 function target

PUSH-TO-ENERGIZE test button (recessed): Press with a non-conductive thin rod to directly drive the output relay for external circuit testing

Neutral wire related control (only for models with neutral wire): NEUTRAL TAP selector, NEUTRAL CAL potentiometer NEUTRAL TIME DIAL、NEUTRAL INST 1、 And NEUTRAL DEFEAT switch (disable neutral overcurrent protection when enabled, LED indicates status)

There is also a time overcurrent characteristic curve selection switch (limited to Z1/Z2/Z3 timing options) and a normal/test sliding switch (only for factory calibration, must be placed in the "normal" position during operation, facing towards the back of the relay) on the right internal circuit board.

Detailed explanation of overcurrent characteristic curve

The core technological value of BE1-51 lies in its rich temporal characteristic library. According to different timing options, the available characteristic curves can be divided into three categories:

4.1 Non integral timing (Z1, Z2 options)

B1~B7: Seven standard inverse time curves: short inverse time limit, long inverse time limit, definite time limit, medium inverse time limit, inverse time limit, even inverse time limit, and extreme inverse time limit

B8: I ² t curve

C1~C8: I ² t with limit range 1~8 (Z1 option only)

E2/E4/E5/E6/E7: BS142 standard curve (Z2 option only), including long inverse time, inverse time, very inverse time, and extreme inverse time

4.2 Integral timing (Z3 option)

The Z3 option uses an integral algorithm to simulate the operating characteristics of an electromagnetic overcurrent relay. Its timing curve corresponds one-to-one with the Z1/Z2 standard curve, but is implemented through time incremental accumulation - it only acts when the accumulated "energy" during the overcurrent duration reaches the preset threshold. This characteristic is closer to the thermal memory effect of traditional electromechanical relays.

4.3 Extended Timing

When selecting the 2-D or 2-E option, the standard delay is multiplied by approximately 5.7 times, which is suitable for cascading protection scenarios that require longer delay coordination.

All curves can be interpolated and selected from the 100 possible curves in each curve chart using the TIME DIAL (00~99) on the front panel. Appendix A shows the trends of each characteristic family with 14 representative curves. Users can switch between up to 16 types of curves through the 16 bit selector switch on the internal circuit board on the right.

Installation and wiring points

BE1-51 adopts the standard S1 chassis size. Attention should be paid during installation:

The grounding terminal at the rear of the chassis must be hard grounded to the ground with a copper wire of not less than 12 AWG

When unplugging the connection plug (1 10 terminal chassis, 2 20 terminal chassis), disconnect the normally open trip circuit first, short-circuit the normally closed circuit first, and then disconnect the power supply and induction circuit to ensure that the CT does not open circuit

The external trip circuit must be disconnected through the 52a contact to prevent inductive overload of the relay contacts

Wiring wire not less than 14 AWG

For equipment that is stored for a long time (as a backup) and contains long-life aluminum electrolytic capacitors, it is recommended to run the capacitor on power for 30 minutes every year to extend its lifespan.

Complete process of on-site testing and calibration

6.1 Test Preparation

Required equipment: Suitable AC/DC power supply, 50/60Hz current source, DC external power supply (for output circuit and timer input), relay protection tester capable of outputting 40A or more, timer, shunt resistor (to provide minimum load current for the target). Connect the test circuit according to the induction input type (K single-phase, G three-phase, H/V three-phase with neutral wire, I/X two-phase with neutral wire) as shown in Figure 5-1~5-4 of the manual.

6.2 Time overcurrent startup test

Set TIME DIAL to 99, INST 1/2 to maximum (clockwise), TAP CAL to maximum (clockwise)

Select A gear for TAP and slowly increase the current until the TIMING indicator light is just on (first adjust CAL counterclockwise until the light is on, then clockwise to the maximum, and then increase the current until the light is on)

Record the starting current value (should be within ± 5% of the TAP A value)

TAP selects J gear for repeated testing and records the maximum starting point (which should be within ± 5% of the J gear value)

Repeat the above steps for each phase and neutral wire model of multiphase/neutral wire

6.3 Timing output accuracy test

TAP selects B mode, TIME DIAL is set to 20

Apply an overcurrent of 5 times the precise TAP B value and start the timer

Find the intersection point between the 5-fold point on the corresponding characteristic curve and the TIME DIAL=20 curve, and read the theoretical delay

The actual timing reading should be within ± 5% of the theoretical value

Time DIAL is set to 40, 60, and 99 for repeated testing

For models with neutral wires, the test signal should be connected to the neutral wire input terminals (17, 18) and the above steps should be repeated

6.4 Transient Overcurrent Start Test

INST 1 is adjusted to the minimum (counterclockwise), corresponding to a startup value of 1 times the TAP A gear value

Slowly increase the current to the output relay of INST 1 and record the current (should be ≤ TAP A value)

INST 1 is adjusted to maximum (clockwise), corresponding to a startup value of 40 times the TAP A gear value

Slowly increase the current from 35 times to the relay action, and record the current (should be>40 times the TAP A value)

Repeat the test on neutral line INST 1 (if any) and INST 2 (if any)

6.5 On site precise calibration steps

If the target startup value falls between the TAP gears, or if the device is equipped with an instantaneous overcurrent option, it is recommended to calibrate accurately on the test bench according to the following steps:

Connect the test bench according to the induction type and use the TIMING indicator light as the start indicator (no output terminal is required)

Apply target starting current

TAP selects the gear closest to the target value and slightly higher, and TAP CAL rotates clockwise to the maximum

After applying current, slowly adjust the TAP CAL counterclockwise until the TIMING indicator light just turns on - completing the startup value calibration

Same operation for neutral wire (for models with neutral wire)

Common troubleshooting guide

Troubleshooting direction

The relay cannot be powered on to check if the voltage at the power terminal meets the nominal/range value of the selected power option (see Table 1-1); Check polarity (DC input has no polarity requirement but needs to be within the range)

TIMING indicator does not light up. Check if the induction input wiring is correct (high/low range terminals); Is TAP CAL in the correct position; Is the neutral wire DEFEAT switch mistakenly set to ON

The position of the timing accuracy out of tolerance confirmation curve selection switch is consistent with the selected curve; Does TIME DIAL correspond to the correct curve family; Test whether the current is accurate to 5 times the TAP value

Whether the momentary component does not move or moves too early, and whether the control potentiometer drifts due to vibration; Check if it is a four turn potentiometer (multiple turns are required to cover the full range)

The target does not maintain a current excitation type target and requires an output circuit of at least 0.2A; check if the target reset switch is stuck; Is the target state recovery function normal after power interruption

Communication/test plug issues: When using the Basler 10095 test plug, it is necessary to confirm that it fits well with the chassis terminals and whether the circuit switching timing is normal when the plug is unplugged

Maintenance and storage recommendations

BE1-51 does not require regular preventive maintenance, but it is recommended to conduct a functional spot check once a year, especially for the validation of start-up values and timing accuracy. For long-term stored backup equipment, due to the presence of aluminum electrolytic capacitors inside, powering on for at least 30 minutes per year can effectively extend the lifespan of the capacitors. If the device malfunctions, please contact Basler Electric technical support to arrange repairs and do not disassemble the circuit board by yourself.