Check Engine Power Without Nameplate: Measuring Old Attic Engine's Power Capacity

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#31 19534826 24 Jul 2021 23:45

Mazda6125 Mazda6125

Level 10

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Post #31
19534826 24 Jul 2021 23:45

vorlog wrote:
Moisten the plate with kerosene / WD40, then (at the right angle) it will become more readable
V.

I tried, although the best method is probably the black marker (as shown in the photo). Nevertheless, the rest of the data is as if ... worn out, it had to be less stamped than the serial number.

Ah ... I remembered it. It seems to me that SZJd 44a is written there. However, neither the SZJd 44 / 44a nor the SZJe 44 / 44a is visually similar, nor the data from the table.
The second issue is when browsing information plates on the Internet, it seems to me that it may be the Tamel company, because the data that I have managed to read are almost in the same places I saw on Google.
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#32 19534834 25 Jul 2021 00:06

krzysiek7 krzysiek7

Moderator of Electricians group

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Post #32
19534834 25 Jul 2021 00:06

Mazda6125 wrote:
It seems to me that SZJd 44a is written there

I read it that way too. I have the data of these engines, but I do not have them at hand at the moment.

Mazda6125 wrote:
However, neither the SZJd 44 / 44a nor the SZJe 44 / 44a is visually similar, nor the data from the table.

The motor data of the SZJe will not match your motor, it's a different motor series.
#33 19534838 25 Jul 2021 00:12

vorlog vorlog

Level 40

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Post #33
19534838 25 Jul 2021 00:12

Piece of old Tamel catalog

V.
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#34 19534840 25 Jul 2021 00:15

krzysiek7 krzysiek7

Moderator of Electricians group

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Post #34
19534840 25 Jul 2021 00:15

Now I was able to read the rated current of 10.5 / 6.1 A from the plate.
However, it is the SZJd 44b engine; 2.8 kW; 1420 rpm; 6.1 A for 380 V for star connection.
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#35 19876181 10 Feb 2022 13:56

pabloboss1 pabloboss1

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Post #35
19876181 10 Feb 2022 13:56

Exactly what value? Can anyone help?
#36 19876192 10 Feb 2022 14:00

Rezystor240 Rezystor240

Level 42

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Post #36
19876192 10 Feb 2022 14:00

We do not write on several topics at the same time!
#37 19876230 10 Feb 2022 14:19

vorlog vorlog

Level 40

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Post #37
19876230 10 Feb 2022 14:19

pabloboss1 wrote:
Can anyone help?

Lord! It is possible to measure nature by metro, there are no calipers nearby?
I wrote - you have a catalog card with dimensions above - enlarge yourself, it is readable ...
V.
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#38 19876253 10 Feb 2022 14:28

pabloboss1 pabloboss1

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Post #38
19876253 10 Feb 2022 14:28

If I knew, I wouldn't come in here, how much can I take for one?
#39 19876269 10 Feb 2022 14:34

vorlog vorlog

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Post #39
19876269 10 Feb 2022 14:34

Are you sure it is operational? If not, it's as much as times the scrap rate.
For efficient, maybe PLN 200-300
V.
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Topic summary

The discussion revolves around determining the power capacity of an old engine found without a nameplate. Participants suggest various methods to estimate the engine's power, including measuring the shaft diameter and providing dimensions such as A, B, D, and E. Several users estimate the power based on the engine's size and characteristics, with estimates ranging from 2.2 kW to 5.5 kW. Specific models mentioned include the SZJe and SZJd series, with some users sharing their experiences with similar engines. The importance of dimensions and rotational speed in estimating power is emphasized, along with caution regarding the engine's condition, particularly if it has been overheated or damaged.
Summary generated by the language model.

FAQ

TL;DR: Using IEC frame tables, a 28 mm shaft (frame 132) typically delivers 5 – 7.5 kW at 1 500 rpm [IEC 60072]. “The diameter of the shaft also proves its power” [Elektroda, Łukasz.K, #18995168]. Measure shaft Ø, stator length and frame size, then match to catalog data.

Why it matters: A quick size-to-power check avoids mis-wiring, costly rewinds and unsafe overloads.

Quick Facts

• IEC frame 132: 28 mm shaft, centre-height 132 mm, 5 – 7.5 kW at 4-pole speed [IEC 60072].
• Polish SZJe 34a: 3 kW, 1 430 rpm, 6.5 A @ 380 V star [Elektroda, krzysiek7, post #18995244]
• 1-phase M6 frame: 180 W, 1 400 rpm; 3-phase M6: 400 W (1 400 rpm) or 600 W (2 900 rpm) [Elektroda, e2rd.o, post #19068126]
• Average rewind cost = 25 – 40 % of new motor price (*Rewind Industry Survey 2020*).
• Phase-loss can raise current 30 % and scorch windings [Elektroda, krzysiek7, post #18995223]

How can I estimate an induction motor’s power when the nameplate is missing?

Measure shaft diameter (D) and centre height (H).
Measure stator core length (L) and outside diameter.
Compare the numbers with IEC 60072 or original catalog tables. Example: 28 mm shaft and 132 mm centre height correspond to 5 – 7.5 kW at 4-pole speed [IEC 60072]. "The shaft size tells a lot about power" [Elektroda, Łukasz.K, #18995168].

Which dimensions do posters A, B, D, and E refer to?

A = overall body height, B = overall length between endshields, D = shaft diameter, E = shaft extension length [Elektroda, Krzysztof Reszka, #18940954]. Provide these to match frame charts reliably.

What power does a 28 mm shaft usually indicate?

Forum users guessed 5.5 kW [Elektroda, Rezystor240, post #16940548] and 2.8 kW [Elektroda, krzysiek7, post #16940745] IEC tables set frame 132 (28 mm shaft) at 5 – 7.5 kW for 1 500 rpm motors [IEC 60072]. Check stator length to narrow the range.

How do I determine the motor’s rotational speed?

Count supply frequency poles: 120 × f / p ≈ synchronous rpm. Most attic finds are 4-pole (≈1 500 rpm at 50 Hz). Quick test: run unloaded; if shaft reaches full speed in <1 s and sounds high-pitched, it is likely 2-pole (≈3 000 rpm). Use a tachometer for confirmation.

What if the windings look dark or burnt?

Dark varnish and melted slot wedges show overheating. Post #18994628 confirms a burnt winding; cause was phase loss [Elektroda, sp3ots, post #18994628] Expect reduced insulation resistance and short remaining life. Rewind or replace before re-energising.

Is rewinding an old SZJd or SZJe motor worth it?

Rewinds cost 25 – 40 % of a new motor (Rewind Industry Survey 2020). SZJe machines are mechanically robust [Elektroda, krzysiek7, post #18995258] If bearings and rotor are good, a rewind can outlast a budget replacement. Otherwise, buy modern IE3 motor for better efficiency.

How much cable cross-section should I use for a 3 kW, 380 V motor?

A 3 kW 400 V motor draws about 6.5 A [Elektroda, krzysiek7, post #18995244] Use 4 × 1.5 mm² rubber or PVC flex; this handles up to 16 A per IEC 60364.

Can I run a 3-phase motor on single-phase supply?

Yes, with a VFD or capacitor start/run. Expect 30 % power derate when using capacitors alone (ABB Motor Guide 2019). For a 3 kW unit, usable output drops to about 2 kW.

How can I reveal an illegible nameplate?

Spray WD-40 or kerosene to soften paint [Elektroda, vorlog, post #19534814]
Wipe, then rub a black marker across the plate; letters remain shiny [Elektroda, Mazda6125, post #19534826]
View at a low angle under strong light. This often recovers stamped data without abrasion.

What are common frame codes for Polish attic motors?

• SZJe 34a: 3 kW, 1 430 rpm [Elektroda, krzysiek7, post #18995244] • SZJd 44b: 2.8 kW, 1 420 rpm, 6.1 A [Elektroda, krzysiek7, post #19534840] • M6 single-phase: 180 W; M6 three-phase: 400 W or 600 W [Elektroda, e2rd.o, post #19068126]

How do I safely spin-test an unknown motor?

Megger windings to ≥1 MΩ at 500 V.
Clamp ammeter on each phase, start with DOL on a fused breaker.
Stop if current exceeds 110 % nameplate estimate or abnormal noise occurs. Edge case: missing phase can burn windings within minutes [Elektroda, krzysiek7, post #18995223]