Supermarket Automatic Label Printing Weight Scale with Barcode

Smart digital retail scale for supermarket fresh food weighing, featuring high precision, intuitive interface, and seamless integration with POS systems.

BUS PROTECTION FUNCTIONS & SYSTEMS

Primary bus protection includes high-speed differential schemes (87B, 87BB, 87Z, 87N, 87ST), restricted earth fault (64REF), and sensitive ground fault (64). Backup protection uses overcurrent (50/51), earth fault (50N/51N/51G), high-set (50HS), negative sequence (46), and directional (67/67N) relays.

Diesel Generator Protection Numbers

Protection relays safeguard generators by preventing damage and ensuring grid stability through reverse power, loss of excitation, unbalanced load, thermal, overcurrent, earth fault, voltage/frequency, and over-fluxing protections.

Differential Protection Function Implemented in Power Systems

Differential protection detects faults by comparing input and output currents of equipment; imbalance triggers a trip signal to isolate the fault. It offers high sensitivity and selectivity.

symmetrical components

Symmetrical components analyze unbalanced three-phase systems: positive sequence (balanced, normal operation), negative sequence (balanced but reverse rotation, causes motor heating), and zero sequence (in-phase, linked to earth faults).

Voltage Transformers (VT) and Capacitive Voltage Transformers (CVT)

VTs use electromagnetic induction for voltage measurement, suited for systems up to 132 kV. CVTs combine capacitive division with electromagnetic transformation, offering higher stability and accuracy, ideal for high-voltage applications.

Earth fault protection (no neutral)

Earth fault protection differs in isolated and resistance-grounded systems: isolated systems use VTs in open-delta to detect voltage displacement (59N relay), enabling fault detection without tripping; resistance-grounded systems allow controlled fault current for reliable relay operation (50N/50G).

Motor Protection Relays – ANSI Numbers

Motor protection relays detect electrical, thermal, and mechanical faults using ANSI codes: 49 (thermal overload), 50/51 (phase overcurrent), 50N/51N (earth fault), 46 (unbalance), 47 (phase failure), 48 (locked rotor).

Generator Protection & Control device function

DG set protection includes electrical (differential, overcurrent, negative sequence, voltage/frequency, reverse power, loss of excitation, V/Hz, lockout) and mechanical (oil pressure, temperature, level, locked rotor, start limits) layers for comprehensive safety.

Current Transformer (CT) vs Potential Transformer (PT)

CTs measure current by stepping down high currents (e.g., 400A to 5A) in series, while PTs measure voltage by stepping down high voltages (e.g., 11kV to 110V) in parallel; both enable safe metering and protection.