Schneider RM17TG00 Phase Sequence & Relais de surveillance de perte de phase

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 contact inverseur (1CO) version; RM17TG20 in the same series is the 2C/O dual-contact model

✅ Core Functions

Monitors three phases L1/L2/L3:

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

Self-powered, energized directly from L1/L2/L3, no additional auxiliary alimentation requis

📋 Key Technical Specifications

🔌 Terminal Wiring Definition

Bornes supérieures: L1, L2, L3 → Connect to three-phase power supply

Lower contact terminals:

11: Commun

14: Normalement ouvert (NON) (closed in normal state, open under fault)

12: Normalement fermé (Caroline du Nord) (ouvert à l'état normal, closed under fault)

With correct three-phase supply and proper phase sequence: le relais s'active, LED ON; Perte de phase / reversed phase → relay de-energizes, LED OFF

🛠️ Scénarios d'application typiques

Hoisting equipment, ascenseurs, lignes de convoyeurs, water pump sets, preventing motor reverse rotation

Compresseurs d'air, chiller unit three-phase power protection

Portable equipment power access detection, emergency power switching judgment

⚠️ Troubleshooting Points

1. LED éteinte: 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 & protection contre les sous-tensions, select RM17TE series.

🧩 Same-series Comparison & Référence de remplacement

RM17TG00: 1CO, séquence de phases + perte de phase

RM17TG20: 2C/O dual changeover contacts, séquence de phases + perte de phase

RM17TE00: With voltage unbalance, surtension, sous-tension, 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

En vigueur: RM17TG00 / RM17TG20 three-phase phase sequence & phase loss relay

Précaution de sécurité: 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. État normal: yellow LED ON, both contact sets energized; Fault state: yellow LED OFF, both contact sets de-energized

1. Pre-check Preparation
2. Outils: Multimètre numérique, cross screwdriver, gants isolants
3. Confirmation du modèle: 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

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

Description: No indicator light after energizing, contacts 11/14 et 21/24 fail to close

1. Éteindre, inspect L1/L2/L3 terminals: Check for looseness, oxidation or poor crimping; clean dust and copper oxide on terminals
2. Allumer, 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

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

Most frequent on-site fault: Séquence de phases inversée

1. Measure three line voltages and confirm all values between 183~484VAC with balanced three-phase voltage
2. Éteindre, swap any two incoming L phases (par exemple. L1 et 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

Symptôme 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 et 21/22/24, both act synchronously

1. Power off and verify contact wiring:

11, 21: Common terminals

14, 24: Normalement ouvert (NON) (closed when energized; open under fault)

12, 22: Normalement fermé (Caroline du Nord) (open when energized; closed under fault)

2. Allumer (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: ouvrir; 11 & 12, 21 & 22: conduire

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

Symptôme 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: Dommages au câble, 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

Symptôme 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, surtension & undervoltage protection required: Replace with RM17TE00 multi-function monitoring relay

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

✅ Step1: Éteindre, inspect appearance and wiring (bornes, marques de brûlure, looseness)

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

✅ Step3: Observe LED status to locate fault domain (alimentation / séquence de phases / 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. Idées fausses courantes
2. ❌Idée fausse: 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. ❌Idée fausse: Front panel adjustment knobs are available for threshold setting

✅ Note: RM17TG has no potentiometer, threshold fixed.

3. ❌Idée fausse: Two contact sets can act independently

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

4. ❌Idée fausse: Can be used in 3P4W system (with neutral wire)

✅ 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. Recommandation d'entretien
7. Periodic inspection: Tighten L1/L2/L3 input terminals and contact terminals quarterly to prevent vibration-induced looseness
8. Conditions ambiantes: Operating temperature -20~+60℃; avoid heavy dust, humid or corrosive gas environment
9. Nettoyage: Clean module surface dust with dry brush after power cut, liquid cleaner prohibited
10. Durée de vie: Mechanical life of contacts >10 millions de cycles; electrical life approx.100,000 cycles at 5A@250VAC

Schneider RM17 Series Three-phase Monitoring Relay Full List (Harmony Zelio, 35mm rail DIN, 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 (Modèle de base: séquence de phases + 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 / PAREMENT / TU / LE (Multi-function adjustable type, transparent cover with adjustment knobs)

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

1. Model Suffix Coding Definition (RM17Txx00)

TG: Type de base, fixed threshold, no adjustment knob, séquence de phases + perte de phase

TT: Adjustable basic model, séquence de phases + perte de phase, voltage range selectable

PAREMENT: T + Asymmetry voltage unbalance detection

TU: T + Undervoltage monitoring

LE: Total full functions (séquence de phases, perte de phase, déséquilibrer, surtension, sous-tension)

00: 1C/O output

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

1. Tableau de sélection rapide (Three-phase models)

1. Common General Specifications
2. Montage: 35mm rail DIN, 1 module (17.5mm);
3. Output Logic: Relay energized (power normal) → contacts closed; fault → contacts open (fail-safe type);
4. Alimentation: Self-powered directly from L1/L2/L3, pas de fil neutre, three-phase 3-wire system only;
5. Temps de réponse: TG fixed ≤130ms; TT/TA/TU/TE fault delay manually adjustable;
6. Contacter l'évaluation: 5A 250VAC resistive load; for PLC DI and contactor interlock circuit, not for direct driving of high-power loads

VII. Remplacement & Upgrade Reference

RM17TG00 ↔ RM17TG20: fonction identique, only contact quantity differs

RM17TT00 → RM17TA00: add voltage unbalance detection

RM17TA00 → RM17TE00: add overvoltage and undervoltage window monitoring

Legacy RM22TG series is substitute series (même fonction, different form factor)