Schneider RM17TG00 Phase Sequence & Relè di monitoraggio della perdita di fase

RM17: Harmony RM17 series three-phase monitoring relay

TG: Monitors phase sequence and phase loss only (no voltage unbalance, overvoltage or undervoltage functions)

00: 1 contatto di scambio (1C/O) versione; RM17TG20 in the same series is the 2C/O dual-contact model

✅ Funzioni principali

Monitors three phases L1/L2/L3:

1. Errore nella sequenza delle fasi (reverse phase, motor reverse rotation protection)
2. Phase loss fault (loss of two or more phases; single-phase weak voltage drop will NOT trigger)

Autoalimentato, energized directly from L1/L2/L3, no additional auxiliary Alimentazione elettrica necessario

📋 Key Technical Specifications

🔌 Terminal Wiring Definition

Terminali superiori: L1, L2, L3 → Connect to three-phase power supply

Lower contact terminals:

11: Comune

14: Normalmente aperto (NO) (closed in normal state, aperto sotto guasto)

12: Normalmente chiuso (NC) (open in normal state, closed under fault)

With correct three-phase supply and proper phase sequence: il relè si eccita, LED ON; Perdita di fase / reversed phase → relay de-energizes, LED OFF

🛠️ Scenari applicativi tipici

Hoisting equipment, ascensori, linee di trasporto, water pump sets, preventing motor reverse rotation

Compressori d'aria, chiller unit three-phase power protection

Portable equipment power access detection, emergency power switching judgment

⚠️ Troubleshooting Points

1. LED spento: No power on three-phase incoming lines or loose wiring;
2. LED fails to energize after power-up: Most likely reversed phase sequence, swap any two L phases;
3. Single-phase voltage drop will not trigger RM17TG00. TG series only detects complete phase loss and does not monitor voltage unbalance. For unbalance/overvoltage & protezione da sottotensione, select RM17TE series.

🧩 Same-series Comparison & Riferimento sostitutivo

RM17TG00: 1C/O, sequenza di fasi + perdita di fase

RM17TG20: 2C/O dual changeover contacts, sequenza di fasi + perdita di fase

RM17TE00: With voltage unbalance, sovratensione, sottotensione, phase loss and phase sequence (full-featured model)

📌 Notes

No potentiometer for threshold adjustment, fixed logic without adjustment knobs;

For three-phase 3-wire system only;

Dry contact output for PLC DI or contactor coil interlock circuit.

Schneider RM17TG20 Troubleshooting Document

Applicabile: RM17TG00 / RM17TG20 three-phase phase sequence & phase loss relay

Precauzioni di sicurezza: High-voltage work must follow power cut & voltage verification. Use qualified high-voltage multimeter and wear insulated protective gear for three-phase voltage measurement.

Product Principle Review: Only monitors phase sequence and complete loss of two or more phases; single-phase voltage drop and voltage unbalance will not trigger protection. Self-powered from L1/L2/L3. Normal state: yellow LED ON, both contact sets energized; Fault state: yellow LED OFF, both contact sets de-energized

1. Pre-check Preparation
2. Utensili: Multimetro digitale, cross screwdriver, guanti isolanti
3. Conferma del modello: RM17TG20, rated monitoring voltage 208~440VAC (limit 183~484VAC), long-term operation above 440VAC is not permitted
4. System Confirmation: Three-phase 3-wire system, no neutral wire connected; this model cannot detect single-phase drop in 3P4W system
5. Basic Status Description: ≤650ms initialization delay after power on; fault response ≤130ms; relay stays de-energized when fault exists, auto-recovers once fault cleared
6. Troubleshooting by Fault Symptom

Sintomo 1: Yellow LED completely off after power-up, relay contacts no action

Descrizione: No indicator light after energizing, contatti 11/14 E 21/24 fail to close

1. Spegnimento, inspect L1/L2/L3 terminals: Check for looseness, oxidation or poor crimping; clean dust and copper oxide on terminals
2. Accendere, measure line-to-line voltage L1-L2, L2-L3, L1-L3 at relay upper terminals with multimeter

Any line voltage ＜183V: Undervoltage on power supply, relay cannot operate; check upstream circuit breaker, fuse and cable breakage

No voltage on two or more phases: Upstream phase loss fault, repair power supply circuit

3. LED still OFF with all three-phase voltages normal:

Check miswiring of L1/L2/L3; confirm power cables are not connected to contact terminals

Inspect module appearance: Cracked housing, burn marks or carbonized terminals → internal damage, replace relay directly

Cross test: Remove relay and connect to known good three-phase supply; if LED remains off, relay is defective

Sintomo 2: Three-phase supply normal, LED stays off, relay continuously reports fault (contacts not energized)

Most frequent on-site fault: Reversed phase sequence

1. Measure three line voltages and confirm all values between 183~484VAC with balanced three-phase voltage
2. Spegnimento, swap any two incoming L phases (per esempio. L1 and L3)
3. Re-energize and observe LED:

LED ON and contacts close: Fault resolved, root cause reversed phase sequence

LED still OFF after twice phase swap: proceed to next step

4. Check for virtual connection with induced voltage: Multimeter shows normal voltage but voltage collapses under load. TG series cannot identify weak single-phase drop, but will trigger phase loss alarm if single-phase voltage falls below 100V
5. Still invalid: Relay internal failure, replace for test

Sintomo 3: LED is ON, but no signal on output contact circuit (no PLC feedback / contactor fails to act)

Power monitoring circuit healthy, fault lies in secondary dry contact circuit

RM17TG20 has two independent changeover contact sets: 11/12/14 E 21/22/24, both act synchronously

1. Power off and verify contact wiring:

11, 21: Common terminals

14, 24: Normalmente aperto (NO) (closed when energized; aperto sotto guasto)

12, 22: Normalmente chiuso (NC) (open when energized; closed under fault)

2. Accendere (relay normal state, LED ON), measure continuity with multimeter:

11 & 14, 21 & 24: should conduct; 11 & 12, 21 & 22: should be open

3. Manually create fault (reverse phase sequence), LED OFF:

11 & 14, 21 & 24: aprire; 11 & 12, 21 & 22: condotta

4. Asynchronous action between two contact sets (one closed, one open): Internal contact damage, must replace relay
5. Contact status correct but no signal on downstream circuit: Check PLC DI module, external interlock circuit, broken secondary wiring or blown fuse

Sintomo 4: Random false tripping during motor operation (LED OFF, protection trip)

1. Monitor three-phase voltage, focus on voltage dip during motor starting:

⚠️ Important Limitation: RM17TG only detects complete loss of two phases; single-phase voltage dip will not trigger protection. Random tripping is mostly caused by instantaneous two-phase power loss or poor connection

2. Inspect main circuit contactor, thermal relay terminals and cable lugs for loose connections, overheating and poor contact under high current
3. Check power cables: Danni al cavo, earth fault or risk of phase-to-phase short circuit
4. EMI Troubleshooting: Relay routed in parallel with power cables; relocate RM17TG away from VFDs and contactors, use separate cable trunking or shielding
5. Confirm supply voltage does not exceed RM17TG20 upper limit 440VAC; use RM17TG00 for 480VAC application
6. Cross replacement test: If fault disappears after installing new relay, original relay is aged and damaged

Sintomo 5: Relay does not alarm with single-phase cut-off (protection no action)

This is NOT a fault, it is inherent design limitation!

RM17TG series only detects loss of ≥2 phases. Single-phase disconnection and single-phase voltage drop cannot trigger protection

If single-phase loss, voltage unbalance, sovratensione & undervoltage protection required: Replace with RM17TE00 multi-function monitoring relay

III. Quick Self-check Procedure (On-site Maintenance Checklist)

✅ Step1: Spegnimento, inspect appearance and wiring (terminali, burn marks, scioltezza)

✅ Step2: Power on and measure L1-L2 / L2-L3 / L1-L3 line-to-line voltages

✅ Step3: Observe LED status to locate fault domain (Alimentazione elettrica / sequenza di fasi / relay itself)

✅ Step4: Power off and swap two L phases to verify reversed phase sequence

✅ Step5: Power off and test continuity of two contact sets to confirm switching logic

✅ Step6: Cross replace relay to confirm whether fault comes from relay or external wiring

1. Idee sbagliate comuni
2. ❌ Idea sbagliata: Relay should protect on single-phase loss

✅ Note: TG series only detects loss of two or more phases; single-phase breakage is not detected.

2. ❌ Idea sbagliata: Front panel adjustment knobs are available for threshold setting

✅ Note: RM17TG has no potentiometer, threshold fixed.

3. ❌ Idea sbagliata: Two contact sets can act independently

✅ Note: Two contact sets operate synchronously; asynchronous action indicates relay damage.

4. ❌ Idea sbagliata: Can be used in 3P4W system (con filo neutro)

✅ Note: For three-phase 3-wire only, neutral wire must NOT be connected.

1. Replacement Criteria (Replace relay if any condition met)
2. L1/L2/L3 supply voltage normal, LED remains OFF after phase sequence swap
3. Two contact sets act asynchronously, contacts burnt or fail to switch
4. Housing or terminals show black burn marks, bulging or carbonization
5. Fault eliminated after installing new relay under same power condition
6. Raccomandazione di manutenzione
7. Periodic inspection: Tighten L1/L2/L3 input terminals and contact terminals quarterly to prevent vibration-induced looseness
8. Ambient condition: Operating temperature -20~+60℃; avoid heavy dust, humid or corrosive gas environment
9. Pulizia: Clean module surface dust with dry brush after power cut, liquid cleaner prohibited
10. Durata di servizio: Mechanical life of contacts >10 milioni di cicli; electrical life approx.100,000 cycles at 5A@250VAC

Schneider RM17 Series Three-phase Monitoring Relay Full List (Harmony Zelio, 35Guida DIN da mm, 17.5mm 1-module width)

All models are self-powered from L1/L2/L3, no auxiliary supply required, 5A@250VAC dry contact output, for three-phase 3-wire system

1. RM17TG (Modello base: sequenza di fasi + phase loss only, no adjustment knobs, fixed threshold)

TG Series Features: No potentiometer, no adjustment window on housing, only yellow status LED; Single-phase voltage drop will not trigger alarm

1. RM17TT / DI FRONTE / TU / IL (Multi-function adjustable type, transparent cover with adjustment knobs)

III. RM17 Series Single-phase / DC Voltage Monitoring (Stessa serie, non three-phase)

1. Model Suffix Coding Definition (RM17Txx00)

TG: Tipo base, fixed threshold, no adjustment knob, sequenza di fasi + perdita di fase

TT: Adjustable basic model, sequenza di fasi + perdita di fase, voltage range selectable

DI FRONTE: T + Asymmetry voltage unbalance detection

TU: T + Undervoltage monitoring

IL: Total full functions (sequenza di fasi, perdita di fase, sbilanciare, sovratensione, sottotensione)

00: 1C/O output

20: 2C/O dual independent changeover contacts (only available for TG series)

1. Tabella di selezione rapida (Three-phase models)

1. Common General Specifications
2. Montaggio: 35Guida DIN da mm, 1 modulo (17.5mm);
3. Output Logic: Relay energized (power normal) → contacts closed; fault → contacts open (fail-safe type);
4. Alimentazione elettrica: Self-powered directly from L1/L2/L3, nessun filo neutro, three-phase 3-wire system only;
5. Tempo di risposta: TG fixed ≤130ms; TT/TA/TU/TE fault delay manually adjustable;
6. Valutazione dei contatti: 5A 250VAC resistive load; for PLC DI and contactor interlock circuit, not for direct driving of high-power loads

VII. Sostituzione & Upgrade Reference

RM17TG00 ↔ RM17TG20: identica funzione, only contact quantity differs

RM17TT00 → RM17TA00: add voltage unbalance detection

RM17TA00 → RM17TE00: add overvoltage and undervoltage window monitoring

Legacy RM22TG series is substitute series (stessa funzione, different form factor)