Switchgear & Cabinet Protection Relays
Flush-mount protection for feeders, busbars and distribution transformers
A user substation does not need a bay controller. It needs a relay that fits the cutout, protects the feeder, the bus and the distribution transformer, and reports over the RS-485 pair already pulled through the switchboard. This flush-mounted relay is built for that job in MV panels up to 35 kV, in vertical or horizontal format.
Protection covers three-stage overcurrent with inverse-time characteristics, three-stage zero-sequence and earth fault, two-stage negative-sequence overcurrent, post-acceleration overcurrent, automatic reclosing, overload trip and alarm, under-frequency load shedding, over and under voltage, zero-sequence overvoltage, second-harmonic blocking, fuse-contactor interlock, trip and close circuit supervision, and VT supervision. Current inputs are 5 A or 1 A nominal over 0.04 to 15 × In, withstanding 2 × In continuously and 40 × In for one second. Setting accuracy is ±3% or better, with inverse-time timing held to ±5% or ±40 ms.
Why it matters
Trip and close circuit supervision plus VT supervision catch the wiring failures that only announce themselves when the relay is finally asked to operate.
Setting accuracy of ±3% and IDMT timing within ±5% or ±40 ms keep the relay inside the margins a real coordination study assumes.
Severity level IV EMC, with 10 V/m radiated RF immunity, level IV ESD, 10 V conducted RF and EFT/burst, is what a relay needs to survive switching in its own cubicle.
Remote setting, group switching, soft-strap control and remote trip/close over RS-485 mean an unattended terminal substation stops requiring a site visit for a setting change.
Second-harmonic blocking prevents a transformer energisation from being read as a fault, which is the classic nuisance trip on a user substation.
Ratings
Supply: 110 / 220 VAC; 24 / 48 / 110 / 220 VDC ±15%
AC nominal: 220 V ±10%
Voltage channels: 3 at 100 VAC or 100/√3 VAC
Current inputs: 5 A or 1 A nominal; 0.04–15 × In; 2 × In continuous, 40 × In for 1 s
ANSI functions: Three-stage overcurrent with IDMT, three-stage zero-sequence/earth fault, two-stage negative-sequence overcurrent, post-acceleration overcurrent, automatic reclosing, overload trip/alarm, under-frequency load shedding, over/under voltage, zero-sequence overvoltage, second-harmonic blocking, fuse-contactor interlock, trip and close circuit supervision, VT supervision
Communications: RS-485 with Modbus-RTU and IEC 60870-5-103, menu-selectable; remote setting, group switching, soft-strap control, remote trip/close
Records: >200 SOE records, >400 system logs, >10 s trip context, graphic programmable logic
Accuracy: ≤±3% setting accuracy; reset ratio 0.95 (over) / 1.05 (under); IDMT timing ±5% or ±40 ms
Environment: −10 °C to +55 °C, 5–95% RH non-condensing, altitude ≤2,500 m
Insulation: Insulation resistance >100 MΩ at 500 VDC; 2 kV power-frequency dielectric; ±5 kV impulse (1.2/50 µs, 0.5 J)
EMC: Severity level IV — 10 V/m radiated RF immunity, level IV ESD, 10 V conducted RF, EFT/burst
Mounting: Flush panel mount, vertical or horizontal format
Accessory: DIN-rail circuit-breaker anti-pumping module for 110 V and 220 V AC/DC control supplies
Standards
IEC 60255-21
IEC 60870-5-103
Modbus-RTU
IEC 61000 EMC series
Applications
User substations up to 35 kV — feeders, busbars, distribution transformers
Industrial and mining plants
Hospitals, schools and large commercial buildings
Unattended terminal substations
Questions engineers ask
Which communication protocol does the switchgear relay use?RS-485 carries either Modbus-RTU or IEC 60870-5-103, selectable from the relay menu, so the same hardware fits a building management system or a utility-style master. Over that link you get remote setting, setting-group switching, soft-strap control and remote trip and close, which removes most routine site visits.
Will the relay survive switching transients inside the cubicle?It is specified to severity level IV, with 10 V/m radiated RF immunity, level IV electrostatic discharge, 10 V conducted RF and EFT/burst immunity. Insulation resistance exceeds 100 MΩ at 500 VDC, the power-frequency dielectric test is 2 kV, and impulse withstand is ±5 kV at 1.2/50 µs and 0.5 J.
Technical documentation
Download HVEX Medium-Voltage Cabinet Protection Relay datasheet (English, PDF)
