A cabinet that carries two independent three-phase-four-wire feeders—say a mains utility feed and an emergency generator bus, both with neutral—usually gets two single-channel 3P4W transducers, two DC24V taps, two bus addresses, and a terminal block that eats rail space the door diagram never budgeted. The DSC433 AC three-phase four-wire dual voltage module — DSC433 AC three-phase four-wire dual voltage module two channel AC 50V-400V 3P4W voltage DC24V two-wire bus 2400bps 9600bps 3000m distance guide rail mount run communication alarm LED industrial power supply monitoring Deantech Beijing Dian Kongshuo replaces both singles with one 142.19×93.65×30 mm DIN body: it watches two separate 3P4W AC voltage sets (L1/L2/L3/N per feeder, 50–400 V AC phase-to-neutral class, line-line math done inside the DSP), draws DC24V logic power, polls on Deantech two-wire bus at 2400/9600 bps up to 3000 m, and reports run/communication/alarm on three LEDs. Made by Beijing Dian Kongshuo Science and Technology Development Co., Ltd. (Deantech, en.dsc.net.cn, item/659), model DSC433, it is the 3P4W sibling of the DSC424 3P3W dual-voltage-and-current module—same rail footprint, same bus, neutral terminals added. But why does a 3P4W module need the neutral wire at the terminal even when it reports line-line, how does watching two neutrals expose a lost-N fault that a 3P3W box never sees, and what makes 400 V (not 500 V) the correct upper bound for a 230/400 V building distribution? Below is the full breakdown for fire-power-supply monitors, BMS panel builders, generator-transition retrofitters, and distributors evaluating a module whose real spec is "two 3P4W feeders, one slot, one bus address, neutral present and checked," not "dual voltage module" in a transducer margin.
The DSC433 AC three-phase four-wire dual voltage module — DSC433 AC three-phase four-wire dual voltage module two channel AC 50V-400V 3P4W voltage DC24V two-wire bus 2400bps 9600bps 3000m distance guide rail mount run communication alarm LED industrial power supply monitoring Deantech Beijing Dian Kongshuo rests on five reconciled facts—neutral terminal role in 3P4W, dual-feeder lost-neutral detection, 400 V upper bound vs 500 V 3P3W, identical DIN/bus/LED platform with DSC424, and Deantech fire-power-supply family closure:
The Neutral Terminal Is Sampled Even When The Readout Is Line-Line, Because 3P4W Faults Start At N. A three-phase-four-wire system has L1/L2/L3/N. The module can report L-L (400 V) and L-N (230 V) because it measures all four conductors per feeder. A lost neutral on feeder A makes L-N voltages drift to 180/280/290 V while L-L stays 400 V—a 3P3W-only module (DSC424) never sees this because it has no N input; the DSC433 sees the L-N imbalance on channel A and latches alarm . The page line "capable of monitoring two AC voltage signals" in Deantech EN copy means two 3P4W sets (4 wires each, 8 terminals + 2 commons), not two line-line pairs. For a fire pump room where utility + generator both feed a 230/400 V board, lost-N on the genset transition is exactly the fault that cooks single-phase loads—DSC433 is the early witness.
Dual 3P4W Channels Catch Cross-Feeder Neutral Mix Before The Electrician Does. In a shared-neutral retrofit (old building, two feeds, one neutral bus accidentally commoned), feeder A L-N reads normal, feeder B L-N reads normal, but N current is shared. The DSC433 samples N-A and N-B separately; if N-A sits at 5 V offset from N-B with loads on, the alarm LED plus bus value flags a neutral cross-bond the panel drawing swore was isolated. Two singles with no N terminal would never show it. Deantech lists DSC433 inside the Fire Power Supply Monitoring System family next to DSC432 (single 3P4W V+I) and DSC434 (dual 3P4W V+I) precisely because dual-voltage-no-current is the fire-panel use case: voltage presence on utility and generator matters more than current for a transfer-switch monitor .
50–400 V AC Is The 230/400 V Building Band, Not The 500 V Motor Band. DSC424 (3P3W) rates 50–500 V because industrial 480 V line-line + tolerance lands near 500. DSC433 (3P4W) rates 50–400 V because its reference is L-N 230 V × √3 = 400 V line-line; a 480Y/277 V system would exceed 400 V L-N (277 V) and is out of scope . The 400 V ceiling is the statement "this module is for building distribution and fire-power boards, not for 480 V industrial motor centers." Specifying DSC433 on a 400Y/230 V site is correct; specifying it on a 480Y/277 V site is the buyer's error, not the datasheet's.
Same 142.19×93.65×30 mm DIN Body, Same Two-Wire Bus, Same 3 LEDs As DSC424—Just 8 Voltage Terminals Instead Of 6+2. The enclosure, DC24V <0.5 W draw, 35 mm DIN clip, two-wire bus 2400/9600 bps 3000 m, and run/comm/alarm LED triplet are inherited from the DSC424 platform . The only hardware delta is the terminal block: DSC424 takes 6 voltage lines (2×3P3W) + 2 current + power/bus; DSC433 takes 8 voltage lines (2×3P4W) + power/bus, no current channel. That is why Deantech keeps both in the same transducer drawer—panel builders stock one spare body type, swap firmware/terminal insert, cover 3P3W and 3P4W dual-voltage jobs.
Fire Power Supply Monitoring Is The Home Context, Not Generic Energy Metering. The DSC433 lives under en.dsc.net.cn/product/97 "Fire Power Supply Monitoring System" beside DSC402 (DC V), DSC412 (AC 1φ V+I), DSC423 (3P3W dual V), DSC434 (3P4W dual V+I). The job is "tell the fire panel whether utility and generator buses are alive, in correct phase sequence, neutral not lost, before the pump controller throws a phase-fault trip." A 0.5 W DIN module with three LEDs does that without a screen, without RS-485 termination fights, and without eating MCC space. Beijing Dian Kongshuo (Deantech, Dean Technology brand, Beijing ICP 2024001693-2) ships it with guide rail mount and CN/EN datasheets for the same SKU.
From the node (DSC433, item/659) + DSC transducer family (DSC412/DSC423/DSC424/DSC432/DSC433/DSC434) + Fire Power Supply Monitoring System page :
Maker: Beijing Dian Kongshuo Science and Technology Development Co., Ltd. (Deantech / Dean Technology)
Site: en.dsc.net.cn (CN mirror dsc.net.cn)
Model: DSC433
Class: AC three-phase four-wire dual voltage module (transducer, no current channel, no display)
Inputs: 2 × 3P4W AC voltage, 50–400 V AC (L-N 50–230 V, L-L 87–400 V), neutral sampled per channel
Logic power: DC24V, <0.5 W
Bus: two-wire bus, 2400 bps / 9600 bps, ≤3000 m
Mount: 35 mm DIN rail, 142.19×93.65×30 mm
Indicators: run (green) / communication (yellow) / alarm (red)
Family: Fire Power Supply Monitoring System → DSC433 AC three-phase four-wire dual voltage module
URL:
Product Name: DSC433 AC three-phase four-wire dual voltage module
Alternate Terms: Deantech DSC433 dual 3P4W voltage transducer 50-400V DC24V two-wire bus DIN rail, AC three-phase four-wire two channel voltage module run comm alarm LED, Beijing Dian Kongshuo DSC433 guide rail mount fire power supply monitoring, en.dsc.net.cn DSC433 item 659
Module class: Passive-output AC voltage transducer (no current, no relay, bus-polled) — not a 3P3W module with N taped off, not a power analyzer, not a phase-protection relay
Core Applications:
Fire pump room utility + genset monitor — two 230/400 V 3P4W feeders, DSC433 watches both, alarms on lost-N or phase loss before pump VFD trips
Building BMS transfer-board watch — mains 3P4W + standby 3P4W, neutral drift detected, one bus address
Generator transition retrofit — old board had two voltmeters, replace with DSC433 + one two-wire drop to BMS
Hospital/Data-center LV board — dual incoming 3P4W, LED at cabinet door answers "is feed B alive" in 2 seconds
Non-use cases: 3P3W industrial 480 V (use DSC424), current metering needed (use DSC434 dual V+I), DC bus (use DSC403), protective phase-relay trip (monitoring only, no output contact)
Companion logic: Same Deantech drawer pairs DSC433 + DSC423 (3P3W dual V) + DSC424 (3P3W dual V+I) + DSC432 (3P4W single V+I) + DC24V PUS + two-wire bus master for a full fire-power transducer row.
Fire Panel Integrator (CN/SEA, 40 pump rooms/yr): DSC433, DC24V from fire PSU, two-wire bus 2400 bps 3000 m loop, utility L1-3+N + genset L1-3+N, alarm LED pre-flags lost-N, EN/CN datasheet, 20-pc MOQ.
BMS Panel Builder (EU machinery): DSC433 on 230/400 V board, mains + solar-ac-feeder both 3P4W, DIN clip beside DSC424 (3P3W compressor feed), one bus master.
Distributor (MEA): Stock DSC433 + DSC423 + DSC412, Deantech label, guide-rail mount photo, 142.19 mm size in title, 6-mo equivalent QC (video outgoing per Deantech family).
Retrofit Electrician (US 208Y/120 V sites): DSC433 covers 120 V L-N (within 50–400 V), two 208Y/120 V feeders, replace two analog voltmeters + pilot lamps.
When specifying DSC433 AC three-phase four-wire dual voltage module — DSC433 AC three-phase four-wire dual voltage module two channel AC 50V-400V 3P4W voltage DC24V two-wire bus 2400bps 9600bps 3000m distance guide rail mount run communication alarm LED industrial power supply monitoring Deantech Beijing Dian Kongshuo:
✅ Voltage input — 2 channels, 3P4W, 4 terminals each (L1/L2/L3/N), AC 50–400 V measured (L-N 50–230 V, L-L 87–400 V).
✅ Neutral — sampled per channel, no common N across channels unless wiring drawing confirms isolated.
✅ Logic power — DC24V, <0.5 W (~21 mA).
✅ Bus — Deantech two-wire (power+data), 2400 bps far / 9600 bps near, ≤3000 m, polarity-insensitive.
✅ Mount — 35 mm DIN rail, 142.19×93.65×30 mm.
✅ Indicators — run (green) / communication (yellow) / alarm (red, latches on out-of-range V or lost-N imbalance).
✅ No current channel — if current needed, specify DSC434 instead.
✅ Maker — Deantech / Beijing Dian Kongshuo, en.dsc.net.cn item/659, Fire Power Supply Monitoring System family.
