GWZC-9621Distribution Transformer Protection Relay​ Product Introduction

          GWZC-9621 Distribution Transformer Protection Relay​ provides comprehensive protection and monitoring for auxiliary, station service, and grounding transformers (≤1600kVA) in ≤35kV systems, delivering phase/ground fault protection and thermal monitoring via integrated measurement functions, typically installed in LV switchgear or protection panels for industrial plants and substations.

GWZC-9621 Distribution Transformer Protection Relay Product functions（ANSI）

1.Composite Voltage Overcurrent Protection (ANSI 50/51/27)
2.Time Overcurrent Protection (ANSI 51)
3.Definite Time Negative Sequence Overcurrent Protection (ANSI 46)
4.Zero Sequence Overcurrent Protection (ANSI 50G/51G)
5.Overload Protection (ANSI 49)
6.Overvoltage Protection (ANSI 59)
7.Undervoltage Protection (ANSI 27)
8.Non-electrical Protection
9.Lockout Protection (ANSI 74)

​Technical Features of Distribution Transformer Protection Relay

          1.Utilizes an internationally advanced high-speed processor operating at 120 MHz. With abundant built-in resources and simplified peripheral circuit design, it ensures superior manufacturing quality and stability. Ample hardware resources include 8MB Flash Memory.
          2.Measures three-phase currents and zero-sequence current (Ia, Ib, Ic, Io), phase or line voltages (Uan, Ubn, Ucn, Uab, Ubc, Uca), active power P, reactive power Q, power factor cosφ, frequency f, active energy kWh, and reactive energy kVarh.
          3.Supports up to 12 user-customizable binary inputs with configurable labels.
          4.Protection element tripping logic is programmable via trip matrix, enabling flexible relay output assignment. All relay outputs can be configured as trip contacts (auto-reset) or alarm contacts (manual reset).
          5.Built-in universal operating circuit compatible with 0.5A–5A tripping/closing currents and AC/DC power supplies.
          6.Supports network-based GPS time synchronization.
          7.Implements reliable TV failure criteria to prevent unintended motor undervoltage protection operation.
          8.Includes one 100M Ethernet port and one RS485 interface, supporting IEC 60870-5-103, Modbus protocols.
          9.Records 16 fault waveforms with up to 13 analog channels sampled at 1ms intervals in standard Comtrade format.
          10.Low static power consumption (≈6W). LCD module employs new technology for significantly extended service life.
          11.High EMC immunity, passing 10 tests including Level IV (highest) standards for fast transients, electrostatic discharge, and surge immunity.
          12.Operating temperature: -25℃ to +55℃ (ensuring clear display and smooth operation).

Technical Specifications and Parameters of Distribution Transformer Protection Relay

1.Rated Electrical Parameters​
Power Supply​
          Operating voltage: AC/DC 86V–264V
          Ripple factor: ≤5%.

Rated Current & Voltage​
          AC current: 5A or 1A;
          AC voltage: 100V or 100/√3V.

​2.Key Technical Indicators​

Accurate Operating Range​
          Current: 0.04In–20In (In=5A or In=1A);
          Voltage: 1V–150V;
          Frequency: 45Hz–60Hz.

​Measurement Accuracy​
          Voltage/current: Class 0.5;
          Active/reactive power, power factor: Class 1.0;
          Frequency: ≤±0.05Hz;

Setting Error​
          Setting value: ≤±3%;
          Operating time error:
          Definite-time protection: ≤(±1% setting +40)ms
          Inverse-time protection: ≤±5% setting or ±40ms.

SOE Resolution​
          <2ms.

Contact Capacity​
          Trip/closing current of operating circuit: 0.5A–5A adaptive; compatible with AC/DC trip circuits.
          Trip dry contact: 8A (make capacity at DC220V);
          Signal dry contact: 5A (make capacity at DC220V).

3.Environmental Conditions​
          Ambient temperature: -25℃ to +70℃;
          Relative humidity: 5%–95% (no condensation/icing internally);
          Atmospheric pressure: 66kPa–106kPa.

4.Power Consumption​
          AC current circuit: ≤0.5VA/phase at In=5A; ≤0.3VA/phase at In=1A.
          AC voltage circuit: ≤0.5VA/phase at rated voltage.
          DC power circuit: ≤10W (normal operation); ≤20W (during activation).

5.Overload Capacity​

AC current circuit:
          2×In continuous
          10×In for 10s
          40×In for 1s.
          AC voltage circuit: 1.4×Un continuous.

6.Insulation Performance​

Insulation Resistance​

          ≥100MΩ between electrified terminals and non-charged metal parts/enclosure, and between independent circuits (measured with 500V megger under standard conditions).

Dielectric Strength​

          Withstands 50Hz AC voltage for 1min without breakdown/flashover (remaining circuits grounded during test).

​Impulse Voltage​

          Withstands 1.2/50μs lightning impulse voltage:
          5kV (open-circuit) between independent circuits or between circuits and ground.

7.Damp Heat Endurance​

Passes GB/T 7261 alternating damp heat test:

          +40±2℃, RH 93±3%, 48h (24h/cycle).
          Insulation resistance measured during last 2h: ≥1.5MΩ;
          Dielectric strength: ≥75% of specified test voltage.