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Three-Phase Voltage Monitor Buying Guide
Verified 2026-09-05 · By VUKAR Editorial Team
Compare the fault list before the price. RM17TE00 lists asymmetry; RM22TR33 lists voltage limits, phase loss, and phase sequence.
- Need asymmetry detection? Check RM17TE00 and its exact threshold method.
- Need high/low voltage checks with two changeover contacts? Review RM22TR33.
- Neither output-current number is a motor horsepower rating.
- Have your panel professional check voltage range, settings, and safe restart.
What do these names mean?
- Harmony is Schneider Electric's relay range name; the full model code identifies the functions.
- A monitoring relay watches supply conditions and changes a control contact when a set condition occurs.
- Phase sequence means the order of the three phases. Phase loss means a missing phase.
- Asymmetry means unequal phase voltages. Check the model's calculation method; it may differ from the calculator.
Write down the job first
- Record the motor, starter or drive, supply voltage, and control-circuit voltage.
- List each needed fault: high voltage, low voltage, missing phase, wrong sequence, or asymmetry.
- Ask a qualified person for readings at the same load state and measurement point.
- Agree alarm, trip delay, reset, and restart behaviour before buying.
- Check the relay's control contacts against the actual starter circuit.
Two exact Harmony models
| Check | RM17TE00 | RM22TR33 |
|---|---|---|
| Rated supply | 208–480 V AC | 380–480 V AC[S1] [S2] |
| High / low voltage | Both listed | Both listed[S1] [S2] |
| Phase loss / sequence | Both listed | Both listed[S1] [S2] |
| Asymmetry function | Listed; confirm its threshold method | Not listed in the cited function table[S1] [S2] |
| Control contacts | 1 changeover | 2 changeover[S1] [S2] |
| Nominal output current | 5 A; check contact duty | 8 A; check contact duty[S1] [S2] |
Products you can evaluate
These are exact technical candidates, not rankings. Both official India pages show buying controls; confirm seller, pincode and stock.
Schneider Electric
Harmony RM17TE00 three-phase multifunction relay
Exact model/variant: RM17TE00
A technical candidate when the reviewed circuit needs the listed asymmetry function and one changeover contact.[S1] [S6]
- 208–480 V AC rated supply
- Asymmetry listed
- 1 changeover contact
Price: Check current price, seller, and pincode availability on the official store.
Seller: Schneider Electric India eShop; confirm fulfilling seller · checked 2026-09-05
Check current price and stockSchneider Electric
Harmony RM22TR33 three-phase control relay
Exact model/variant: RM22TR33
A technical candidate for documented high/low voltage, phase-loss, and sequence checks with two changeover contacts.[S2] [S5]
- 380–480 V AC rated supply
- 2 changeover contacts
- High/low voltage detection
Price: Check current price, seller, and pincode availability on the official store.
Seller: Schneider Electric India eShop; confirm fulfilling seller · checked 2026-09-05
Check current price and stockRead these specifications carefully
| Term | Plain meaning | What to confirm |
|---|---|---|
| Supply range | Voltages the model is rated for | Your actual three-phase supply[S1] [S2] |
| Changeover contact | A contact switches between two paths | Required alarm and starter circuits[S1] [S2] |
| Delay | Wait before a defined action | Exact fault, delay range, and recovery[S1] [S2] |
| Asymmetry threshold | Level that triggers the relay's unequal-voltage function | Formula, percentage basis, and equipment limit[S1] [S3] |
A percentage is a clue, not a setting
- The tool calculates maximum voltage deviation from the average of three line-to-line readings.
- That NEMA-style result is not automatically the relay's asymmetry setting.
- The RM17TE00 sheet states its asymmetry adjustment against selected nominal voltage. Ask the designer to compare methods.
- Quick pause: do you need a number to read, or an action that stops the machine?
- These relay examples do not establish a numeric panel-display function.
Ask before placing the order
- Will the invoice and delivered relay show this exact model code?
- Can I read the current datasheet and instruction sheet?
- Does the model explicitly list every fault we need?
- What happens after power returns or the voltage recovers?
- Can its contacts control our starter at the required voltage and switching duty?
- Who will test the settings and safe restart after installation?
- What are the current stock, delivery, warranty, and return terms?
Compare the functions you will use
- These models differ in supply range, contacts, and listed fault functions.
- Compare the complete installed cost, including enclosure work, wiring, and testing.
- Do not read 8 A as permission to connect a motor directly.
- The RM22TR33 official India store shows an Add to cart action. Confirm seller and pincode availability.
- The RM17TE00 official India store also shows Add to cart. Final price and stock need confirmation.
Keep panel work with qualified people
Do not open, probe, wire, bypass, or adjust live equipment using this guide. A qualified professional must check installation and safe restart.[S1] [S2] [S4]
A monitoring relay does not by itself replace overload, short-circuit, or other required protection. Test the complete protection and starter circuit.[S1] [S2] [S4]
Quick questions
Is phase loss the same as voltage unbalance?
No. A missing phase and unequal phase voltages are different conditions. Require the exact function needed; a general protection label is not enough.[S1] [S2] [S3]
This comparison covers only the listed models, criteria, sources, and verification date. Omission or missing public data is not a negative judgement about any brand.
Related VUKAR resources
References used for this guide
- RM17TE00 product data sheet — Schneider Electric; accessed 2026-09-05
- RM22TR33 product data sheet — Schneider Electric; accessed 2026-09-05
- Energy Management for Motor-Driven Systems: voltage unbalance — United States Department of Energy; accessed 2026-09-05
- Electrical safety regulations 2023 — Central Electricity Authority; accessed 2026-09-05
- RM22TR33 official India store — Schneider Electric; accessed 2026-09-05
- RM17TE00 official India purchase page — Schneider Electric; accessed 2026-09-05
