Setting and troubleshooting of Basler BE1-27/59 voltage relay

Basler BE1-27/59 Voltage Relay Setting and Field Troubleshooting Guide

In the power system, abnormal voltage (under voltage or over voltage) is one of the main causes of motor burnout, transformer overexcitation, misoperation of automatic transfer switches, and disconnection of distributed power sources. The Basler BE1-27 (undervoltage), BE1-59 (overvoltage), and BE1-27/59 (undervoltage/overvoltage combination) series solid state relays, with wide range tuning, flexible time characteristics (instantaneous, timed, inverse time), and high anti-interference ability, have long served industrial distribution, power plants, and cogeneration grid points. However, on-site engineers often encounter problems such as incorrect conversion of setting values, improper selection of time curves, and unfamiliarity with testing procedures when commissioning or replacing old relays. This article is based on the complete technical manual of this series, systematically sorting out its application scenarios, key parameters, panel operations, testing and calibration, and typical fault handling, providing relay maintenance personnel with an engineering manual that can be checked and used immediately.

Overview of Product Series and Selection

BE1-27 is an undervoltage relay, BE1-59 is an overvoltage relay, and BE1-27/59 is an undervoltage/overvoltage combination relay. All three are solid-state and use a drawer style S1 chassis with a panel containing potentiometers, indicator lights, and test buttons. The model is defined by the "Style Number" encoding and includes the following options:

Voltage detection range: Range 2 (55-160V, suitable for 120V/69V systems), Range 3 (110-320V, suitable for 240V/208V/277V systems), Range 4 (1-40V, used for open delta zero sequence voltage detection).

Time characteristics: instantaneous (I), timed limit (D, adjustable from 0.1 to 9.9 seconds), inverse time limit (short/medium/long curves).

Output contact configuration: normally open/normally closed, independent or combined.

Auxiliary power supply: DC 24V/48V/125V or AC 120V/240V wide range input.

When selecting, it is necessary to clarify: the protected object (motor, transformer, busbar), voltage level, whether it needs to have both undervoltage and overvoltage functions, and whether it needs instantaneous and delayed two-stage protection (such as allowing short-term undervoltage during motor start-up).

Typical application scenarios and tuning logic

2.1 Motor undervoltage protection

When the motor starts, the bus voltage may briefly drop. If the drop amplitude is too large or the duration is too long, the motor will not be able to accelerate to the rated speed, resulting in overcurrent heating. BE1-27 can be set with a fixed time limit (such as 0.5-2 seconds) or an inverse time limit (the deeper the drop, the faster the action), and will only trip when the voltage remains below the set value to avoid starting impact misoperation.

2.2 Automatic Transfer Switch (ATS) Voltage Monitoring

In a dual power supply system, BE1-27 detects the loss or low voltage of the main power supply and issues a switching command after a delay; BE1-59 monitors whether the backup power supply voltage has returned to the normal range to prevent reclosing on live equipment. The manual states that undervoltage relays are commonly used for "trip transfer" logic, while overvoltage relays are used for "normal recovery" supervision.

2.3 Grid Connection Interface Protection (Cogeneration)

When a distributed power source (such as a gas turbine) is connected in parallel with the power grid, if the circuit breaker on the grid side trips, the distributed power source may operate independently with load, causing the risk of asynchronous reclosing. BE1-27 monitors the line voltage. If the line is still live (maintained by distributed power sources), it will be locked and reconnected to prevent grid impact. Meanwhile, BE1-59 can detect overvoltage caused by capacitor switching and promptly cut off distributed power sources.

2.4 Transformer overexcitation protection

When a transformer operates under overvoltage or low frequency, the magnetic flux density of the iron core increases, causing a sharp increase in excitation current and overheating of the winding. BE1-27/59 can set the overvoltage setting (such as 110% rated) and cooperate with inverse time characteristics to delay tripping during overexcitation, avoiding transformer damage.

2.5 Grounding Fault Detection (Open Triangle Method)

In a three-phase three wire system, if configured as a grounded star open delta PT, the zero sequence voltage increases in the event of a single-phase grounding fault. BE1-59 (or BE1-27/59 overvoltage unit) is connected to an open delta winding and can detect grounding faults in low current grounding systems through sensitive tuning (range 4, 1-40V).

Interpretation of Key Electrical Parameters

3.1 Voltage detection input

Range 2: 55-160Vac (nominal 120V system), with a continuous overload capacity of 1.5 times.

Range 3: 110~320Vac (nominal 240V/277V system).

Range 4:1-40Vac (dedicated for zero sequence voltage).

Internally, a step-down transformer is used for isolation, with extremely low power consumption (<1VA).

3.2 Time characteristics and curves

Instantaneous: Response time<50ms (under voltage) or<80ms (over voltage), used to immediately cut off severe voltage abnormalities.

Time limit: adjustable from 0.1 to 9.9 seconds (step size 0.1 seconds), suitable for coordination with lower level protection.

Inverse time limit: Provide short, medium, and long curves (see manual figures 3-2 to 3-7), with action time decreasing with voltage deviation and better matching with equipment thermal capacity.

3.3 Output contact capacity

DC resistance: 1.0A @ 125VDC; DC inductance: 0.3A @ 125/250VDC (L/R=0.04).

Communication: 7.5A @ 208VAC.

Short time on-off capability: 30A/0.2s (200Vdc).

Attention: Current type target indication requires a circuit current of ≥ 200mA to trigger.

3.4 Auxiliary power supply

Table 1-1 lists various types of power sources (K/J/L/Y/Z), covering DC 24-280V and AC 120-240V, suitable for different on-site power conditions. When the power supply loses power, the power status contact (normally closed) closes the alarm.

Front panel control and indicator light instructions

The panel layout (Figure 2-1) includes:

Undervoltage setting potentiometer (A): Set the delayed undervoltage action value.

Undervoltage delay dial (B): The timing limit is set to 0.0 to 9.9 seconds; Inverse time selection curve slope.

Instantaneous undervoltage setting (C): Independently set the instantaneous undervoltage action value.

Overvoltage setting (D), overvoltage delay (E), overvoltage instantaneous (F): same as the undervoltage side.

Power indicator light (G): red LED.

Target reset button (H): Reset the electronic latch LED target.

Overvoltage/undervoltage indicator lights (I, L): Indicates that the corresponding function has been activated.

Target indicator (J): The red LED is locked when the trip output is triggered.

Output test button (K): The output relay can be manually operated by pressing it with an insulating rod for circuit verification.

Functional principle description

After internal PT voltage reduction, low-pass filtering (suppressing>226Hz noise), and full wave rectification, the system voltage is compared with the reference voltage of each potentiometer. When the voltage exceeds the overvoltage threshold or falls below the undervoltage threshold, the corresponding comparator triggers a timer. If the duration reaches the delay setting, the drive output relay will trip. The instantaneous function bypasses the timer and acts directly.

Priority: In BE1-27/59, the undervoltage function takes priority over the overvoltage function (when both are met, undervoltage output takes priority).

Inverse time curve: Figures 3-2 to 3-7 in the manual show six curves for undervoltage (short/medium/long) and overvoltage (short/medium/long), with the horizontal axis representing the percentage difference between voltage and setting value and the vertical axis representing the action time. Users can select one of the different curve families through the delay dial.

Key points for on-site installation and wiring

Chassis: S1 semi embedded or protruding installation, dimensions are shown in Figure 4-1 to 4-12, and the shell must be grounded with ≥ 12AWG copper wire (terminal "GND").

AC connection: The typical wiring is shown in Figure 4-16. The voltage detection input is connected to the PT secondary side, paying attention to phase and polarity (for open delta mode).

DC control circuit: Figure 4-17, the output contacts are connected in series to the trip coil or alarm circuit.

Caution: If the connection plug is unplugged, the relay will lose its protective function and must be operated under stable conditions. Before conducting insulation testing, it is necessary to remove the plug to avoid damaging the internal circuit.

On site testing and calibration steps (excerpted from Section 5 of the manual)

High precision variable frequency voltage source (frequency stability better than 0.00002Hz, phase noise<90dB), oscilloscope or timer are required for testing.

7.1 Startup value (Pickup) test

Regarding Scope 3 (120V system, undervoltage):

Turn all undervoltage settings to the lowest and overvoltage settings to the highest.

Apply voltage to the rated value (such as 120V).

Slowly reduce the voltage, observe the undervoltage indicator light and record the voltage - it should be 54-56Vac (45% to 47% of the rated 120V, set by the manufacturer).

Then turn the undervoltage setting to the highest, reduce the pressure, and record the action value - it should be between 156.8 and 163.2 Vac (near the upper limit of range 3). This step verifies the setting range.

Similarly, for overvoltage testing, boost the voltage to the operating point (range 3 overvoltage upper limit is approximately 156.8~163.2Vac).

Range 4 (1-40V) is used for grounding detection, and the test voltage is low, requiring a adjustable voltage source.

7.2 Time Delay Verification

Set the delay dial to "00" (instantaneous), apply step voltage (under voltage or over-voltage jump), and measure the output action time to be ≤ 50ms (instantaneous).

Set the delay dial to "01" (0.1 seconds), and the timed limit type should measure 0.05-0.15 seconds; If set to "99" (9.9 seconds), the measured time is 9.70-10.10 seconds.

Inverse time limit type: Corresponding to a specific curve, test according to column 1 (short delay) and column 2 (long delay) in Table 5-4. For example, the action time of the undervoltage short inverse time limit should be 0.087-0.187s in the 0.1s range and 6.23-6.69s in the 9.9s range.

Note: During testing, it is necessary to wire according to Figure 5-2, generate a step through the S1/S2 button, and measure the contact closure time with a timer.

Common fault phenomena and troubleshooting ideas

Possible causes of malfunction, inspection and resolution

The voltage is normal but the undervoltage indicator light is on. The setting value is set too high (close to the rated voltage); Compare the measured PT voltage with the panel setting value using a multimeter for PT secondary circuit abnormalities (voltage drop); Reduce the undervoltage setting value

Overvoltage does not operate. The overvoltage setting value is set too high, or the PT ratio is incorrect. Check the system rated voltage and relay range; Check if the wiring is missing phase

The action time does not match the set time limit. If the dial is not reset to zero or the inverse time limit curve is selected incorrectly, verify the dial number and magnification, and refer to the curve diagram for confirmation

The output contact is not closed but the indicator light is on. The output relay coil is damaged or the contact is burned; Manually operate the test button to open the external trip circuit and check the continuity of the contacts; If normal, check the external circuit

If the target indicator is not lit and it is a current type target, a current of ≥ 200mA is required; Or internal latch circuit fault confirmation tripping circuit current; Test using internal triggering method (if selected)

The power indicator light is not on, and the auxiliary power supply is missing or the power module is faulty. Check if the terminal voltage meets the rated range; Measure power output (+12V/-12V)

Replacement selection and upgrade suggestions

When it is necessary to replace old-fashioned electromechanical voltage relays (such as GE IJV, Westinghouse VRS) on site, the BE1-27/59 series can be directly replaced, but attention should be paid to:

Input voltage range: The old style may have multiple taps, while the BE1 series provides continuous adjustable range, which needs to be selected according to the actual PT secondary voltage (2/3/4).

Time characteristics: Electromechanical systems are mostly time limited, and BE1 provides inverse time limit options, which need to be re adjusted according to protection coordination.

Contact capacity: The BE1 series has low DC arc breaking ability (0.3A inductive), and if driving large intermediate relays, contactors or solid-state relays need to be installed.

Dimensions: The S1 chassis size is compatible with most older models, but the opening size needs to be confirmed.

If digital functions such as communication and event recording are required, Basler BE1-FLEX or DECS series digital relays can be considered, but the cost is high and this series can be temporarily used for non emergency modifications.

Maintenance and Storage

Regular verification: It is recommended to conduct a startup value and delay test once a year, record data and compare it with the last time, and monitor drift.

Cleaning: Keep the panel and terminals clean and dry to avoid insulation degradation caused by dust accumulation.

Storage: When spare parts are stored for a long time, they should be powered on for 30 minutes each year to maintain the performance of the internal electrolytic capacitor (as clearly indicated in the manual).

Repair: If the fault cannot be resolved, contact Basler technical support to obtain a repair number. Do not disassemble or repair the circuit board on site.