Schneider RM17TG00 — 3-Phase Relay Specs and Buyer's Guide

By Abdullah Zahid
14 min read
Schneider RM17TG00 Harmony 3-phase control relay mounted on 35mm DIN rail for industrial motor protection panel

Schneider RM17TG00 3-Phase Control Relay, Harmony Control Relays Series: Specifications, Alternatives and Buyer's Guide

Controls engineers and panel builders specifying three-phase motor protection need a relay that does exactly one job without ambiguity: detect phase loss and phase reversal before a motor winding burns. The Schneider RM17TG00, part of the established Harmony RM17 Series, is a modular DIN rail monitoring relay rated for 183–528V AC supply input, with a 5A SPDT output contact, automatic restart, and a compact 17.5mm single-module footprint. If your facility voltage falls within that range and you need phase loss plus phase sequence detection in a panel-mounted format, this is a straightforward specification — and the review below will confirm or redirect that decision in under five minutes.

If you have already confirmed this is the right part, check current pricing and availability at LeadTime.ca — ships worldwide.

Who Should Buy the RM17TG00 — and Who Shouldn't

The Schneider RM17TG00 is the correct choice for engineers and buyers who can confirm all of the following:

  • Incoming three-phase supply voltage is within 183–528V AC — this is a hard boundary, not a guideline
  • A single SPDT (1 Form C: 1NO + 1NC) output contact is sufficient for the load circuit — solenoid coil, contactor coil, or alarm beacon drawing no more than 5A AC
  • A 35mm DIN rail is present and available in the target panel — this relay has no alternative mounting option
  • Screw terminal wiring connections are acceptable — spring or rapid-connect termination is not available on this model
  • Phase loss and phase sequence reversal detection are the required monitoring functions — phase unbalance, overvoltage, and under-voltage detection are not included in this model

If your facility supply exceeds 528V AC, or if you need phase unbalance detection, do not order the RM17TG00. The RM17UG00 covers phase unbalance, and the RM17XE00 targets higher-voltage applications — both are referenced in the variant comparison section below.

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What the RM17TG00 Actually Does in a Live Panel

The Schneider RM17TG00 is a continuously active monitoring device, not a switched-mode controller. Once wired to all three incoming AC phases at its L1, L2, and L3 input terminals, the relay watches the supply in real time. If one phase drops to zero — due to a utility fault, blown fuse, loose terminal, or tripped breaker — the relay detects phase loss and switches its SPDT output contact. That contact switch then triggers whatever downstream action the panel is designed to take: cutting power to a motor contactor coil, activating a fault beacon, or initiating a controlled shutdown sequence.

Phase sequence monitoring is the second active function. The relay confirms that the three AC phases are arriving in the correct rotational order. A reversed phase sequence — which can occur after utility work or following a miswired reconnection — causes three-phase motors to rotate in the wrong direction. In a pump application, that means pumping the wrong way. In a conveyor, it means material moving backward. The RM17TG00 catches this before the motor is energized and holds the output contact open until the correct phase order is restored.

The auto-restart function adds practical value in facilities with momentary utility fluctuations. Rather than tripping permanently on a brief glitch, the relay applies a 1.5-second delay before re-engaging after a fault clears. This prevents nuisance shutdowns during sub-second utility disturbances without masking genuine phase failures. An LED status indicator on the relay face gives the panel technician immediate visual confirmation of whether the relay is in a healthy or faulted state — no multimeter required for initial status check.

One function the RM17TG00 does not perform: phase unbalance detection. If the three phases are all present and in correct sequence but carrying meaningfully different voltages, this relay will not flag it. That distinction matters and is addressed directly in the variant comparison below.

Where the RM17TG00 Sits in a Typical Motor Protection Circuit

The RM17TG00 occupies the monitoring and protection layer between the incoming three-phase supply and the motor starter or contactor. It does not switch high-current motor power directly — its 5A output contact operates pilot circuits, not the main motor circuit.

  • Upstream: Three-phase utility supply or generator output, through main disconnect and branch circuit protection (fuses or breaker) — this relay requires upstream overcurrent protection
  • Relay input (L1, L2, L3): Phase monitoring relay receives all three incoming phases at screw terminals on the 35mm DIN rail
  • Relay output (COM, NO, NC): SPDT output contact drives the motor contactor coil, alarm relay, or shutdown circuit — load current must not exceed 5A AC
  • Downstream load: Three-phase motor, compressor, or pump receives power through the contactor; contactor is held open if relay detects a phase fault
  • Indication: LED on relay face shows phase-good or phase-fault status; panel-mounted beacon or HMI alarm can be driven from the same output contact loop

Industries and Applications That Specify This Relay

The most common application is upstream motor protection in manufacturing facilities. A three-phase motor running on only two phases draws excessive current in the remaining windings, generating heat that degrades insulation rapidly. The RM17TG00 detects the single-phasing condition and interrupts the contactor coil circuit before winding damage occurs. At 100,000 rated electrical switching operations, the relay is built for the industrial duty cycle of motor control panels.

In water and wastewater pump stations, the relay monitors three-phase supply integrity to prevent pumps from running on degraded power. When a phase fault is detected, the relay can trigger a secondary pump start or activate an alarm to the SCADA system, maintaining system pressure while operations staff respond. The -40 to +70°C operating temperature range means the relay functions across the full climate envelope typical of outdoor pump station cabinets.

HVAC and compressor protection is a significant secondary use case. Scroll and reciprocating compressors are damaged quickly by single-phasing, and the cost of a failed compressor exceeds the cost of the monitoring relay by orders of magnitude. The RM17TG00's 17.5mm width allows it to fit into existing compressor control panels alongside contactors and overload relays without requiring panel redesign.

In CNC machine tool and industrial lathe applications, the relay functions as a safety interlock preventing spindle start-up when three-phase supply is compromised. Combined with phase sequence monitoring, it also prevents reverse spindle rotation after maintenance reconnections — a safety-critical function in machining environments.

Data centers and facilities with generator backup power use the relay to confirm clean three-phase supply integrity during and after utility-to-generator switchover, preventing attempts to start critical loads on a faulted or incomplete three-phase feed.

Application Typical Deployment
Three-phase motor protection Installed upstream of motor starter contactor in MCC or local panel; cuts contactor coil on phase loss
Water / wastewater pump station Monitors pump supply; triggers alarm relay or activates standby pump on phase fault detection
HVAC compressor control Wired into compressor control panel on DIN rail; prevents compressor start on reversed or lost phase
CNC and machine tool safety Spindle motor circuit interlock; relay holds spindle enable off when phase fault or reversal is present
Generator backup coordination Confirms three-phase supply integrity post-switchover before critical load contactors are permitted to close
Industrial manufacturing line Conveyor or process line motor protection; phase reversal detection prevents backward motion after reconnection

Electrical Ratings and Purchase-Decision Specifications

Parameter Value
Rated Supply Voltage (Input) 183–528V AC
Supply Frequency 50 / 60 Hz
Contact Configuration SPDT — 1 Form C (1NO + 1NC)
Rated Contact Voltage 250V AC / 30V DC
Rated Contact Current 5A AC / 7A DC
Maximum Switching Capacity 1,250 VA
Monitored Functions Phase loss + Phase sequence reversal only
Auto-Restart Time Delay 1.5 seconds
Operating Temperature Range -40 to +70°C (-40 to +158°F)
Mounting 35mm DIN rail — screw terminals, 6 terminals total (L1, L2, L3, COM, NO, NC)

Full technical specifications are available on the product page at LeadTime.ca.

RM17TG00 vs RM17UG00 vs RM17XE00: Which Variant Do You Actually Need?

Model Monitored Functions Supply Voltage Range Contact Rating Choose When
RM17TG00 Phase loss + Phase sequence 183–528V AC 5A AC / 7A DC SPDT Phase loss and reversal detection only; standard industrial voltage; 5A load circuit
RM17UG00 Phase loss + Phase sequence + Phase unbalance 183–528V AC Higher contact rating (7A DC) Phase unbalance detection required; VFD input protection; larger solenoid or contactor coil load
RM17XE00 Phase loss + Phase sequence + Overvoltage / Undervoltage Higher-rated variant Per model specification Facility voltage exceeds 528V AC; overvoltage or undervoltage protection required alongside phase monitoring

If your load circuit draws more than 5A or your facility supply exceeds 528V AC, the RM17TG00 is not the correct model — check current availability of Harmony RM17 variants at LeadTime.ca to confirm the right fit before ordering.

Expert Verdict: Is the RM17TG00 the Right Relay for Your Project?

The Schneider RM17TG00 is the right relay for panel builders and controls engineers who need a proven, globally certified three-phase monitoring device in a compact DIN rail format — and whose application is specifically phase loss and phase reversal detection. With 100,000 rated electrical switching operations and 30,000,000 mechanical operations, the relay is built for indefinite industrial service at the duty cycles typical of protective monitoring. The 1.5-second auto-restart delay is a practical feature that reduces nuisance trips during brief utility disturbances without compromising fault detection. CSA, UL, CE, C-Tick, and GOST certifications mean a single SKU qualifies for deployment across North American, European, Australian, and other major markets — a genuine advantage for panel builders supplying OEM equipment internationally.

Where the RM17TG00 reaches its limits: it does not detect phase unbalance — voltage imbalance across the three phases — which matters in VFD input circuits and sensitive process equipment. For those applications, the RM17UG00 is the correct model. Facilities with 600V three-phase supply (common in Canadian industrial plants) are outside this relay's 528V AC rated maximum; those applications require the RM17XE00 or a step-down transformer in the monitoring circuit. Single-phase or two-phase systems cannot use this relay at all. And if the downstream load circuit draws more than 5A AC, the SPDT contact rating is the binding constraint — the RM17UG00's higher contact rating becomes the deciding factor.

From a procurement standpoint, the RM17TG00 is a well-stocked part at authorized Schneider Electric distributors worldwide with standard lead times running one to two weeks in normal conditions. For mission-critical applications or build schedules with tight timelines, working with a specialist industrial automation distributor means you get current stock confirmation, datasheet cross-referencing, and application guidance in one interaction rather than multiple back-and-forth exchanges with a general marketplace. Check current pricing and lead time for the RM17TG00 at LeadTime.ca — we ship worldwide and can confirm availability against your project schedule before you commit to an order.

For volume pricing or to confirm lead time before committing to a build, contact the LeadTime.ca team directly — we ship worldwide.

What Engineers Need to Know Before Ordering the RM17TG00

The Schneider RM17TG00 belongs to the Harmony RM17 product family — a mature, stable series of modular monitoring relays that has been in continuous production for decades. Because the product is well-established and commissioning issues are genuinely rare when the relay is specified correctly, there is minimal public forum discussion on this SKU. That absence of community noise is itself informative: this is not a product that generates troubleshooting threads because it does not generate many problems. But the ordering mistakes that do occur are consistent and preventable.

The most common source of ordering errors with the RM17TG00 is the Harmony RM17 family structure itself. The family contains multiple models that look nearly identical in physical form and DIN rail footprint but differ in which fault conditions they monitor. Buyers researching phase monitoring relays sometimes land on the RM17TG00 and assume it monitors everything — phase loss, phase sequence, phase unbalance, and voltage levels. It monitors the first two only. Engineers specifying protection for VFDs, sensitive process loads, or equipment where voltage imbalance causes early bearing or insulation failure need to step across to the RM17UG00. This is the single most consequential specification error to avoid.

The second recurring issue is voltage range verification. The 183–528V AC rated input range covers most standard industrial three-phase services — 208V, 230V, 380V, 400V, 415V, 480V — but it does not cover 600V AC, which is standard in many Canadian industrial facilities. A relay ordered without verifying facility voltage and installed on a 600V system is an out-of-specification installation regardless of how well everything else is done. That verification takes two minutes with a multimeter at the disconnect. It is the single most important step in the pre-order process, and it should be documented on the procurement requisition. When community discussion is sparse and support resources are limited, specialist distributor advice fills that gap — and it is precisely the verification step where a conversation with a knowledgeable distributor before ordering prevents a costly return or commissioning delay.

Wiring and Installation Overview

The RM17TG00 mounts and wires in a straightforward sequence. Engineers requiring full step-by-step wiring procedures and terminal torque specifications should refer to the Schneider Electric installation datasheet supplied with the relay. The following points cover the key requirements for a correct installation:

  • Mount the relay on a 35mm DIN rail by aligning the back clip and sliding until the relay locks with an audible click — confirm the relay cannot slide freely after engagement
  • Connect all three incoming phase conductors to input terminals L1, L2, and L3 using 0.5–2.5 mm² wire — all three inputs must be connected; leaving any terminal open defeats phase loss detection on that conductor
  • Connect the output load circuit to the correct contact pair: COM + NO for a load that must de-energize on phase fault; COM + NC for a load that must energize (alarm) on phase fault — reversing this connection inverts relay behavior
  • Confirm the DIN rail is properly bonded to the panel ground bus before energizing — accurate phase monitoring depends on correct grounding
  • After first energization, verify the LED status indicator is in the healthy state before connecting any motor or load; simulate a phase fault during commissioning by temporarily disconnecting one input to confirm output contact switching and LED state change

Wrong-Part Prevention Checklist

Before placing your order for the Schneider RM17TG00, verify every item on this checklist. These are the exact conditions that cause returns, commissioning delays, and misapplication in the field:

  1. Confirm your supply voltage falls within 183-528V AC range - voltages outside this window will not operate relay
  2. Verify phase sequence monitoring is needed - if you only need phase loss detection, confirm RM17TG00 function set matches your application
  3. Check that 1 Form C (SPDT) contact output is correct for your load - do not confuse with models offering 2NO/2NC or different contact arrangements
  4. Confirm DIN rail mounting is available in your panel - if you need panel-mount or plug-in alternatives, this is wrong product
  5. Ensure 5A contact current is sufficient - if solenoid or bypass contactor draws more than 5A, select a higher-rated relay
  6. Verify screw terminal connection is acceptable - do not order if spring terminals or rapid-connect are mandatory in your design
  7. Do not assume phase unbalance or overvoltage/low-voltage protection is included - this model detects phase loss and sequence only

If any item on that checklist raises a question, contact the LeadTime.ca team before ordering — we can cross-reference the correct Harmony RM17 variant for your application and confirm availability in one step.

Frequently Asked Questions

Will the RM17TG00 detect a voltage imbalance if all three phases are present but unequal in voltage?

No. The RM17TG00 monitors phase loss (complete loss of one phase) and phase sequence reversal only. It does not detect phase unbalance — a condition where all three phases are present but carry meaningfully different voltages. If phase unbalance detection is required for your application, the RM17UG00 is the correct model to specify.

Can the RM17TG00 be used on a 600V AC three-phase supply common in Canadian industrial facilities?

No. The relay's rated supply voltage input is 183–528V AC. A 600V AC supply exceeds this rating and the relay will not operate correctly and may be damaged. For 600V applications, specify the RM17XE00 or consult LeadTime.ca to confirm the correct higher-voltage Harmony RM17 variant for your facility.

Does the RM17TG00 replace an overload relay or provide motor overcurrent protection?

No. The RM17TG00 is a phase monitoring device — it detects phase loss and phase reversal in the incoming three-phase supply. It does not measure motor current and does not replace a thermal overload relay or electronic overload function in a motor starter. A complete motor protection circuit must include a separate overload protection device upstream or integral to the motor starter.

What does the LED indicator on the relay face communicate, and how do I read a fault condition?

The LED status indicator provides visual confirmation of phase status on the relay face. In normal operation with all three phases present and in correct sequence, the LED shows the healthy state. When a phase loss or phase reversal is detected, the LED changes state — providing immediate visual identification of a fault without requiring a multimeter at the terminals. During commissioning, this indicator is the first confirmation that the relay is receiving all three phases correctly.

Is there a delay before the RM17TG00 trips on a phase fault, or does it trip instantaneously?

The relay features a 1.5-second auto-restart delay that applies when a fault condition clears — preventing nuisance re-trips during brief utility disturbances. Phase fault detection response is designed to catch genuine phase loss conditions. For full trip timing specifications, refer to the Schneider Electric datasheet available through the product page.

Is the RM17TG00 the same product as one previously listed under the Square D brand?

Schneider Electric acquired Square D, and some legacy part numbers and branding from the Square D portfolio appear in older BOM references and panel documentation. The RM17TG00 is the current Schneider Electric catalog number for this product in the Harmony RM17 Series. If you are sourcing a replacement for a Square D-branded phase monitoring relay, verify the specifications match before ordering to confirm compatibility with your existing panel wiring and control circuit.

Why Order From LeadTime.ca

  • LeadTime.ca ships the Schneider RM17TG00 and Harmony RM17 Series variants worldwide — no regional restrictions on sourcing
  • Specialist industrial automation focus means application questions — voltage range verification, variant selection, compatible accessories — are answered before the order is placed, not after it arrives
  • Hard-to-find parts and lower-volume SKUs sourced across authorized distributor networks; not limited to popular catalog items only
  • Volume pricing available for panel builders and OEMs — contact for current pricing on multi-unit orders
  • Current stock and lead time confirmed before order commitment — relevant when build schedules are tight and backorder delays are not acceptable

RM17TG00 At-a-Glance Summary

  • Supply voltage input: 183–528V AC — must be verified against facility three-phase service before ordering
  • Output contact: SPDT (1 Form C, 1NO + 1NC), rated 5A AC / 7A DC, 250V AC / 30V DC, 1,250 VA maximum switching capacity
  • Monitored functions: Phase loss and phase sequence reversal only — phase unbalance, overvoltage, and undervoltage are not monitored
  • Auto-restart delay: 1.5 seconds after fault clears — prevents nuisance shutdowns during brief utility disturbances
  • Mounting: 35mm DIN rail only, screw terminals (0.5–2.5 mm² wire), 17.5mm body width single-module footprint
  • Durability: 100,000 rated electrical switching operations; 30,000,000 rated mechanical operations
  • Operating temperature: -40 to +70°C (-40 to +158°F); 95% relative humidity per IEC 60068-2-30
  • Certifications: CE (EU), CSA (Canada), UL (North America), C-Tick (Australia), GOST, RoHS compliant — single SKU qualifies for global deployment
  • Product family: Harmony RM17 Series — compatible form factor with RM17UG00 and RM17XE00 variants for applications requiring additional monitoring functions
  • Pricing: Available on the product page at LeadTime.ca — contact for volume pricing on multi-unit orders

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