Schneider RM17TA00 3-Phase Multifunction Supply Monitoring Relay

(Phase Sequence / Phase Loss / 3-Phase Voltage Unbalance)

Series: Zelio Control / Harmony RM17T Series, DIN rail mounted 3-phase monitoring relay, commonly known as phase sequence protector.

✅ Monitoring Functions

Phase sequence detection (L1-L2-L3): Instant trip upon reverse phase sequence

Phase loss detection: Instant trip if any phase is lost (including phase loss with regenerated voltage from motors)

3-phase voltage asymmetry (unbalance): Adjustable threshold from 5% to 15% of Un, with time-delayed tripping

Logic rule: Phase reversal / phase loss → instantaneous trip; voltage unbalance → delayed trip.

📌 Key Electrical Specifications

Monitoring voltage range: AC 208～480V (operating limit: 183～528V AC)

Frequency: 50/60 Hz (±10%)

Output contact: 1 C/O (SPDT), 5A / 250VAC

Time delay adjustment: 0.1～10s (only for unbalance faults)

Reset delay: Approx. 1.5s

Power consumption: ≤22VA @ 400V 50Hz

Mounting: DIN 35mm rail; width 17.5mm (1 module width)

Indication: Status LED; sealed transparent cover prevents accidental parameter changes

🧮 RM17T Series Selection Comparison (Key for Model Selection)

RM17TT00: Phase sequence + phase loss (NO unbalance monitoring)

RM17TA00 (Current Model): Phase sequence + phase loss + 3-phase voltage asymmetry

RM17TU00: Phase sequence + phase loss + undervoltage

RM17TE00: Phase sequence + phase loss + asymmetry + overvoltage + undervoltage (full-function model)

🛠️ Typical Application Scenarios

Elevators, hoisting & conveying equipment, air compressors, water pumps, refrigeration units, packaging machinery; prevents motor reverse rotation, burnout from phase loss, and overheating caused by three-phase unbalance.

🔌 Wiring Guidelines

1. Connect L1/L2/L3 directly to the monitored three-phase supply (self-powered, no separate auxiliary supply required).
2. Terminals 15/16/18 form one changeover contact: 15-16 = normally closed; 15-18 = normally open.
3. Panel setting: First select rated voltage (208/220/380/400/415/480V), then set unbalance threshold and fault delay time.
4. Fault recovery: Automatic reset once power returns to normal; no manual reset button.

⚠️ Troubleshooting

Relay does not energize after power-up: Check phase sequence, phase loss, and voltage range dip switch setting.

Frequent tripping during normal operation: Increase unbalance percentage threshold, extend time delay, and investigate single-phase load current imbalance.

No LED illumination: Three-phase input voltage exceeds the 183~528V operating range.

📎 Replacement Options

Direct upgraded replacement within the same product line: RM22TA33 (RM22 series, same functions with 2 C/O contacts).

Domestic alternatives: Chint / Delixi three-phase phase-sequence & unbalance monitoring relays.

1. Full Model List of RM17T Series

(3-phase supply monitoring relays, 17.5mm single-module width, DIN rail mounting)

1) Basic Model: RM17TG (Only phase sequence + phase loss; no unbalance / undervoltage monitoring)

RM17TG00: 1 C/O changeover contact, 208～480V AC

RM17TG20: 2 C/O dual changeover contacts, 208～440V AC

2) Multifunction Models (RM17TT / TA / TU / TE, 208～480V AC, 1 C/O contact uniformly)

Abbreviation explanation:

TU = T + Undervoltage

TE = T + Everything (full functions)

III. Common Specifications for the Whole Series (All Models Identical)

Voltage range: AC 208～480V (operating limit 183～528V)

Contact rating: 5A / 250VAC; RM17TG00/TT/TA/TU/TE = 1 C/O; only RM17TG20 = 2 C/O

Width: 17.5mm (1P module)

Reset mode: Automatic reset after fault clears; no manual reset button

1. Upgraded Replacement Models (RM22 Series with Extra Contacts)

RM17TA00 → RM22TA33 (2 C/O contacts)

RM17TU00 → RM22TU23

RM17TE00 → RM22TE33

RM17TA00 Overall Dimensions (W × H × D)

17.5 mm × 90 mm × 72 mm

Width: 17.5 mm (1-pole module, same width as 1P MCB)

Height: 90 mm

Depth (from DIN rail front face): 72 mm

Mounting: DIN35 standard rail

Net weight: Approx. 0.13 kg

✅ All models in RM17T series (RM17TT00 / RM17TU00 / RM17TE00 / RM17TG00) share identical dimensions.

Core Positioning of RM17TA00

It provides phase sequence + phase loss + three-phase voltage unbalance protection, mainly for three-phase asynchronous motors. It prevents reverse rotation, motor burnout from phase loss, and overheating caused by long-term voltage imbalance. Self-powered, compact 1-module DIN rail design, ideal for compact control cabinets and retrofitting projects where no PLC signal collection is needed.

1. Industry & Equipment Applications
2. Hoisting & Conveying (Primary Application)

Overhead cranes, electric hoists, belt conveyors, stackers, elevators; prevents motor reverse rotation after phase reconnection and overheating damage to gearboxes and motors due to long-term unbalance.

2. Elevators & Lifting Platforms

Freight elevators, simple lifting platforms, parking lift power circuits; wrong phase sequence causes reverse car movement; voltage unbalance leads to excessive temperature rise of traction motors.

3. Water Pumps & Pumping Stations

High-power centrifugal pumps, submersible sewage pumps, pre-power monitoring before variable-frequency drives; unbalance is frequently caused by mixed single-phase loads in water supply, sewage treatment and chiller pump systems.

4. Air Compressors & HVAC Refrigeration Units

Screw air compressors, water chillers, air-source heat pumps, refrigeration compressors; compressors are highly sensitive to three-phase unbalance, which easily burns out motor windings.

5. Packaging, Textile & Woodworking Automation

Packaging lines, textile machinery, extruders, injection molding auxiliary equipment; frequent power maintenance and phase swapping require phase sequence verification before power-on.

6. Fan Loads

Exhaust fans, induced draft fans, drying fans; large inertia fans produce regenerated voltage after phase loss; this model supports phase loss detection under regenerated voltage conditions.

7. Control Panels & OEM Equipment Matching

380V three-phase control cabinets, non-standard automation OEM factory-fitted protection; old equipment retrofits, hard-contact interlock without adding PLC analog modules.

1. Selection Boundary: Suitable / Unsuitable Scenarios

✅ Recommended:

Three-phase motor loads with risks of voltage asymmetry overheating (core advantage over RM17TT00)

Supply voltage AC 208~480V, 50/60Hz

Limited cabinet space, only 1 module width available

Hard-contact interlock directly wired into main contactor coil circuit

❌ Not recommended:

Overvoltage + undervoltage monitoring required → choose RM17TE00

Only undervoltage protection without unbalance → choose RM17TU00

Dual independent alarm contacts required → upgrade to RM22TA33 (2C/O)

Motors behind variable-frequency drives: VFDs already have built-in phase loss & unbalance protection; extra relay is generally unnecessary.

III. Typical Control Logic

Contact wired in series with the main contactor coil circuit:

Normal power supply → relay energizes and closes, contactor power permitted;

Phase reversal / phase loss / voltage unbalance detected → relay de-energizes and opens, cutting off main power, with dry contacts available for PLC or audible-visual alarm signals.