Beckwith M-0359 synchronous inspection relay

M-0359 monitors the following four types of conditions internally, and only closes the closing relay when all conditions are met (except for dead wire/dead bus mode):

Voltage amplitude condition:

The voltage of Line and Bus must be ≥ Lower Voltage Limit and ≤ Upper Voltage Limit (two independent checks).

Meanwhile, | Vbus - Vline | ≤ Delta V Limit.

Three voltage related LEDs (BUS UPPER/OWER OK, LINE UPPER/OWER OK, DELTA V OK) are all illuminated.

Delta F Limit condition:

Measure the frequency difference (slip) on both sides, and when it is ≤ the set value (0.01~0.5Hz continuously adjustable), the DELTA F OK LED will light up.

Phase Angle Limit:

Measure the phase angle difference (absolute value) of the voltage on both sides. When it is ≤ the set value (0~± 30 °, other ranges can be customized), the ANGLE OK LED lights up.

Phase angle detection is static and does not consider the direction of slip (i.e. sign). As long as the absolute value is less than the limit, it is allowed.

Dead line/dead bus mode (enabled through external contacts):

If Dead Line Close is enabled, when the Line voltage is lower than DEAD LINE LIMIT (10~60V), the phase angle and frequency difference are ignored, and closing is allowed (but at least one side voltage is greater than 100V to ensure relay action).

Similarly, Dead Bus Close takes effect when the Bus voltage is below DEAD BUS LIMITED.

Attention: When both are activated simultaneously, dead wires and dead busbars will not occur simultaneously (the system will not close when there is no power on both sides).

When all allowable conditions are met and the synchronization check enable (TB1-24/26) is valid, the closing relay (TB1-17~19) closes and outputs a closing command.

Setting values and tuning methods

All settings are completed through the front panel knob, without the need for auxiliary power or instruments. The calibration accuracy of the scale is as follows:

UPPER VOLTAGE LIMITED (110~140V): ± 2% of full scale.

LOWER VOLTAGE LIMITED (90~120V): ± 2% of full range.

DELTA V LIMITED (1-5V, other ranges optional): ± 5% full range.

DEAD LINE/BUS LIMITED (10~60V): ± 7% of full scale.

Phase Angle Limit (0~± 30 °, other ranges optional): ± 5% full range.

DELTA F Limit (0.01~0.5Hz): ± 5% of full scale.

Setting steps (recommended):

Set the Upper/Lower limits based on the rated voltage of the system, for example, if 125V ± 10%, set Upper=137V and Lower=112V.

According to the allowed steady-state pressure difference, Delta V is usually set at 2-3V (corresponding to approximately 2-3kV on the primary side).

Set the phase angle limit (e.g. 15 °) based on the maximum allowable impulse power when the system is parallel, taking into account the system impedance and circuit breaker capacity.

Set a frequency difference limit (e.g. 0.1Hz) based on the system's frequency modulation capability to ensure that the circuit breaker does not close frequently during low-frequency oscillations.

If dead line/dead bus is required, set the Dead Line/Bus threshold (usually 30-40V, indicating that the line has significantly lost voltage).

Phase angle offset function: The phase angle limit can be changed through external contacts (TB1-15/21). For example, if the switch needs to be closed at 15 ° during normal operation and relaxed to 30 ° during emergency, select a 1/2 ratio for ordering, set the panel knob to 30 °, and close the contacts normally (making the limit value 15 °), and open the contacts in emergency (restoring 30 °). On the contrary, if a normal angle of 15 ° is required and a special working condition is narrowed to 3 °, then a 1/5 transformation ratio is selected, the panel is set to 15 °, and the contact is closed in emergency situations (the limit is changed to 3 °).

Analog output and SCADA interface

M-0359 provides 5 analog outputs (Bus voltage, Line voltage Delta V、 Phase angle Delta F）， The output type can be voltage type (0~10V DC) or current type (0~5mA DC), please specify the option when ordering. The voltage type can be directly connected to the AI module of RTU or PLC, while the current type is suitable for long-distance transmission.

Output characteristics (voltage type standard):

Phase angle: 0.0556 V/°, 10V corresponds to ± 180 ° (absolute value, i.e. 0~180 ° corresponds to 0~10V).

Voltage: 0.05 V/V, 7.5V corresponds to 150V rms.

Delta V: 0.5 V/V, 10V corresponds to 20V rms (if other ranges are selected, please consult the factory).

Delta F: 20 V/Hz, 10V corresponds to 0.5Hz.

Current type modification: Users can connect resistor R3 in series at the output terminal of the internal operational amplifier to achieve voltage current conversion. The manual provides the calculation formula for R3 (see Equations 2-4 and Table 1). For example, if 1mA is required for phase angle output corresponding to 180 °, then R3=(1V/1mA) * 1000=1k Ω. It should be noted that the maximum output current is 5mA, and the output voltage of the operational amplifier is limited to 12V. It is necessary to verify that I × (R1+RS+R3) ≤ 12V.

Status contacts (light load): There is a set of normally open/normally closed contacts for voltage status, phase angle status, and frequency difference status, which can be used for SCADA to query the reason for locking or access panel indicator lights.