Thytronic NC020
Protection relay for capacitor banks and harmonic filters with unbalance, peak overvoltage and overcurrent protection.
The Thytronic NC020 is a protection relay for capacitor banks and harmonic filters that guards against overcurrent, earth faults, unbalance from failed capacitor elements and capacitor peak overvoltage. This Modbus RTU template reads the phase currents, unbalance current, capacitor peak voltages, breaker position, trip flags and counters, and lets you change thresholds and send store, reset and compensation commands from ModbusCloud.
- Protocol
- Modbus RTU
- Connection
- RS485, 9600 baud
- Registers
- 153, read and write
- Brand
- Thytronic
- Key readings
- Phase currents · RMS phase currents · Unbalance current · Capacitor peak voltages · Breaker position · Trip flags · Start and trip counters · Remaining discharge time
- Available commands
- Protection thresholds · Time curves and operate times · Unbalance compensation · Discharge time · Breaker open and close · Store, reset and test commands
- Compatible models
- NC020
- Last updated
Registers (153)
147 read, 90 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| Phase Current L1 | A | Read | |||
| Phase Current L2 | A | Read | |||
| Phase Current L3 | A | Read | |||
| Phase Current L1 RMS | A | Read | |||
| Phase Current L2 RMS | A | Read | |||
| Phase Current L3 RMS | A | Read | |||
| Unbalance Current | A | Read | |||
| Compensated Unbalance Current | A | Read | |||
| Unbalance Current Angle | ° | Read | |||
| Residual Current (Calculated) | A | Read | |||
| Capacitor Peak Voltage L1 (x Un) | Read | ||||
| Capacitor Peak Voltage L2 (x Un) | Read | ||||
| Capacitor Peak Voltage L3 (x Un) | Read | ||||
| Remaining Discharge Time | s | Read | |||
| Protection Trip Flags | Read | ||||
| Breaker Position | Read | ||||
| Input IN1 (52b) | Read | ||||
| Input IN2 (52a) | Read | ||||
| Input IN3 (Reset) | Read | ||||
| Self-Test Level | Read | ||||
| Oscillography Recorder State | Read | ||||
| Unbalance Compensation Magnitude | A | Read | |||
| Settings Command | Write | ||||
| Reset Command | Write | ||||
| Breaker Command | Write | ||||
| Unbalance Compensation Command | Write | ||||
| Test Command | Write | ||||
| Recorded Data Default Command | Write | ||||
| Modbus Address | Read and write | ||||
| RS485 Baud Rate | Read and write | ||||
| Measurement Reading Mode | Read and write | ||||
| Phase CT Primary Current | A | Read | |||
| Unbalance CT Primary Current | A | Read | |||
| Fault Record Select | Read and write | ||||
| Event Record Select | Read and write | ||||
| I> Time Curve | Read and write | ||||
| I> Inverse Pickup (x In) | Read and write | ||||
| tI> Inverse Time Setting | s | Read and write | |||
| I> Definite Pickup (x In) | Read and write | ||||
| tI> Definite Operate Time | s | Read and write | |||
| tI> Reset Time | s | Read and write | |||
| I> Cold Load Mode | Read and write | ||||
| I> Cold Load Time | s | Read and write | |||
| I> Definite Cold Load Pickup (x In) | Read and write | ||||
| I> Inverse Cold Load Pickup (x In) | Read and write | ||||
| I>> Time Curve | Read and write | ||||
| I>> Inverse Pickup (x In) | Read and write | ||||
| tI>> Inverse Time Setting | s | Read and write | |||
| I>> Definite Pickup (x In) | Read and write | ||||
| tI>> Definite Operate Time | s | Read and write | |||
| tI>> Reset Time | s | Read and write | |||
| I>> Cold Load Mode | Read and write | ||||
| I>> Cold Load Time | s | Read and write | |||
| I>> Definite Cold Load Pickup (x In) | Read and write | ||||
| I>> Inverse Cold Load Pickup (x In) | Read and write | ||||
| I>>> Definite Pickup (x In) | Read and write | ||||
| tI>>> Definite Operate Time | s | Read and write | |||
| tI>>> Reset Time | s | Read and write | |||
| I>>> Cold Load Mode | Read and write | ||||
| I>>> Cold Load Time | s | Read and write | |||
| I>>> Definite Cold Load Pickup (x In) | Read and write | ||||
| IE> Pickup (x In) | Read and write | ||||
| tIE> Operate Time | s | Read and write | |||
| tIE> Reset Time | s | Read and write | |||
| IE> Cold Load Mode | Read and write | ||||
| IE> Cold Load Time | s | Read and write | |||
| IE> Cold Load Pickup (x In) | Read and write | ||||
| IE>> Pickup (x In) | Read and write | ||||
| tIE>> Operate Time | s | Read and write | |||
| tIE>> Reset Time | s | Read and write | |||
| IE>> Cold Load Mode | Read and write | ||||
| IE>> Cold Load Time | s | Read and write | |||
| IE>> Cold Load Pickup (x In) | Read and write | ||||
| IN>AL Pickup (x INn) | Read and write | ||||
| tIN>AL Operate Time | s | Read and write | |||
| IN>AL Cold Load Mode | Read and write | ||||
| IN>AL Cold Load Time | s | Read and write | |||
| IN>AL Cold Load Pickup (x INn) | Read and write | ||||
| IN> Pickup (x INn) | Read and write | ||||
| tIN> Operate Time | s | Read and write | |||
| IN> Cold Load Mode | Read and write | ||||
| IN> Cold Load Time | s | Read and write | |||
| IN> Cold Load Pickup (x INn) | Read and write | ||||
| IN>> Pickup (x INn) | Read and write | ||||
| tIN>> Operate Time | s | Read and write | |||
| IN>> Cold Load Mode | Read and write | ||||
| IN>> Cold Load Time | s | Read and write | |||
| IN>> Cold Load Pickup (x INn) | Read and write | ||||
| U> Peak Voltage Pickup (x Un) | Read and write | ||||
| tU> Operate Time | s | Read and write | |||
| tU> Reset Time | s | Read and write | |||
| U> Cold Load Mode | Read and write | ||||
| U> Cold Load Time | s | Read and write | |||
| U> Cold Load Pickup (x Un) | Read and write | ||||
| U>> Peak Voltage Pickup (x Un) | Read and write | ||||
| tU>> Operate Time | s | Read and write | |||
| tU>> Reset Time | s | Read and write | |||
| U>> Cold Load Mode | Read and write | ||||
| U>> Cold Load Time | s | Read and write | |||
| U>> Cold Load Pickup (x Un) | Read and write | ||||
| U>>> Peak Voltage Pickup (x Un) | Read and write | ||||
| tU>>> Operate Time | s | Read and write | |||
| tU>>> Reset Time | s | Read and write | |||
| U>>> Cold Load Mode | Read and write | ||||
| U>>> Cold Load Time | s | Read and write | |||
| U>>> Cold Load Pickup (x Un) | Read and write | ||||
| I<< Phase Logic | Read and write | ||||
| I<< Pickup (x In) | Read and write | ||||
| tI<< Operate Time | s | Read and write | |||
| Discharge Time | s | Read and write | |||
| Discharge Start By Undercurrent | Read and write | ||||
| Breaker Failure Triggers | Read and write | ||||
| Breaker Failure Time | s | Read and write | |||
| Breaker Contact Check | Read and write | ||||
| Unbalance Compensation Magnitude Setting | A | Read | |||
| Relay K1 Functions | Read | ||||
| Relay K2 Functions | Read | ||||
| Relay K3 Functions | Read | ||||
| Relay K4 Functions | Read | ||||
| Enable TX Delay | ms | Read | |||
| Oscillography Pre-Trigger | Read | ||||
| Start Count I> | Read | ||||
| Start Count I>> | Read | ||||
| Start Count I>>> | Read | ||||
| Start Count IE> | Read | ||||
| Start Count IE>> | Read | ||||
| Start Count IN>AL | Read | ||||
| Start Count IN> | Read | ||||
| Start Count IN>> | Read | ||||
| Start Count U> | Read | ||||
| Start Count U>> | Read | ||||
| Start Count U>>> | Read | ||||
| Start Count I<< | Read | ||||
| Trip Count I> | Read | ||||
| Trip Count I>> | Read | ||||
| Trip Count I>>> | Read | ||||
| Trip Count IE> | Read | ||||
| Trip Count IE>> | Read | ||||
| Trip Count IN>AL | Read | ||||
| Trip Count IN> | Read | ||||
| Trip Count IN>> | Read | ||||
| Trip Count U> | Read | ||||
| Trip Count U>> | Read | ||||
| Trip Count U>>> | Read | ||||
| Trip Count I<< | Read | ||||
| Faults Stored | Read | ||||
| Selected Fault Number | Read | ||||
| Events Stored | Read | ||||
| Selected Event Number | Read | ||||
| Oscillography Records Stored | Read | ||||
| Clock Year | Read | ||||
| Device Identification | Read | ||||
| Product Code | Read |
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If a device is not in the library yet, we build the template for free as soon as we have the register data.
Use cases
- Show the phase currents, RMS currents and unbalance current of each bank on a dashboard and keep a year of history per value.
- Set an alarm on the compensated unbalance current to see failing capacitor elements before the unbalance element trips.
- Follow the capacitor peak voltages to see how harmonics load the bank over the day.
- Send an e-mail or webhook alert as soon as the trip flags rise above zero.
- Check thresholds and operate times remotely and adjust them during commissioning.
Installation
Wire the rear RS485 port of the NC020 to the RS485 port of the ModbusCloud Gateway, A to A and B to B, and terminate the bus at both ends with 120 Ω.
On the relay, open the Communication menu and note the address and baud rate (default 1 and 9600 baud).
In ModbusCloud, add a Modbus device on the RS485 port of the Gateway with the same address, 9600 baud, 8 data bits, no parity and 1 stop bit.
Import the Thytronic NC020 template and check that the phase currents and the unbalance current come in.
Compare the currents with the relay display, and set the phase and unbalance CT primary currents on the relay if you read primary amps.
Things to watch for
The Gateway gets no answer from the NC020. What should I check?
Check that the address and baud rate on the relay match the device in ModbusCloud, that you use the rear RS485 port and not the front port, and that A and B are not swapped. Terminate the bus with 120 Ω at both ends.
The currents do not match the relay display. Why?
With the default Reading Direct the relay reports primary amps, calculated from the phase and unbalance CT primary currents set under Set, Base. With Reading Relative it reports multiples of the rated current. Check both settings on the relay and compare again.
I wrote a new threshold, but it is gone after a restart. Why?
The NC020 keeps changed settings in temporary memory until it receives the store command. After writing new values, write Store to the Settings Command register, or Clear to discard the changes. Read a setting first before you write it, so you know the current value.
Some values stay empty while the currents come in. Is that normal?
The clock, the identification, the stored compensation and the fault and event records are part of larger messages that the relay may only send as a whole. The template fits NC020 relays with identification code 103 or 109; code 108 uses a different layout.
Can a command from ModbusCloud switch the capacitor bank?
Yes. Breaker Command opens or closes the breaker through the output relays assigned to CB Open and CB Close, and a test with trip operates the output relays. Use them only during commissioning or maintenance. Store the unbalance compensation only on a healthy bank, because the present unbalance becomes the new reference.
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