355M & 355L Frame Motors: Models, Sizes

DRG Motor's cast iron housing with a 355 mm shaft height carries 8 models: on 355M the DRG-355M1-6, DRG-355M-6 and DRG-355M2-6 (6-pole; 160, 185 and 200 kW), plus the DRG-355M-2 and DRG-355M-4 (250 kW); on 355L the DRG-355L-6, DRG-355L-2 and DRG-355L-4 (250–315 kW). 2-pole models have a 75×140 mm shaft, 4- and 6-pole models a 100×170 mm shaft. Common dimensions are H 355 mm, A 610 mm, C 254 mm, and the B5 flange has P 800 mm.

Grey DRG three-phase cast iron electric motor – illustrative image for 355M and 355L frame models

All eight models belong to the three-phase asynchronous electric motors range, and their product pages are in the online motor shop. A motor of this size usually drives a large fan, a pumping station, a compressor or a mill, and is mostly bought to replace an existing unit. So this article is less a catalogue tour than a guide to which dimension decides what in a replacement order.

355M1, 355M, 355M2 and 355L: what the codes mean

On the 355 frame the letters carry two pieces of information. M and L give the housing length, i.e. the lengthwise spacing of the foot holes. On the 6-pole 355M models, the 1 or 2 after the M separates power steps within the same frame: DRG-355M1-6 160 kW, DRG-355M-6 185 kW, DRG-355M2-6 200 kW. All three share the same B3 dimensions, shaft (100×170 mm) and bearings (6322-C3) in the product records; you tell them apart by the nameplate power and current, not with a tape measure. That is why "355M" alone is not enough to replace a 6-pole motor — we need the full type or the kW.

Model (frame)	Power	Poles / speed class / rated speed	Shaft D×E (mm)
DRG-355M1-6 (355M)	160 kW / 200 HP	6-pole / 1,000 / 990 rpm	100×170
DRG-355M-6 (355M)	185 kW / 248 HP	6-pole / 1,000 / not in record	100×170
DRG-355M2-6 (355M)	200 kW / 270 HP	6-pole / 1,000 / 990 rpm	100×170
DRG-355M-2 (355M)	250 kW / 340 HP	2-pole / 3,000 / 2,982 rpm	75×140
DRG-355M-4 (355M)	250 kW / 340 HP	4-pole / 1,500 / 1,490 rpm	100×170
DRG-355L-6 (355L)	250 kW / 340 HP	6-pole / 1,000 / 990 rpm	100×170
DRG-355L-2 (355L)	315 kW / 430 HP	2-pole / 3,000 / 2,982 rpm	75×140
DRG-355L-4 (355L)	315 kW / 430 HP	4-pole / 1,500 / 1,490 rpm	100×170

"1500 rpm" or "3000 rpm" is the speed class (synchronous speed); the rated speed on the nameplate is different, e.g. 1,490 rpm on the DRG-355M-4 and 2,982 rpm on the DRG-355M-2. The product record of the DRG-355M-6 does not list rated speed, current or torque; please confirm these values with us before choosing that model.

Same kW, different frame: the 160, 200, 250 and 355 kW trap

On this frame, power alone does not identify the housing. In the DRG range, 160 kW and 200 kW exist on the 355 frame only as 6-pole motors; their 2- and 4-pole counterparts are on the 315L frame. 250 kW appears in three versions: 2-pole and 4-pole on 355M, 6-pole on 355L. Another mix-up comes from the name itself: DRG's 355 kW models are not on the 355 frame but on 400L / 400M (DRG-400M-2 and DRG-400M-4 and DRG-400L-6).

Power and speed class	Model on the 355 frame	DRG model on another frame
160 kW – 1,000 rpm	DRG-355M1-6	—
160 kW – 1,500 rpm	—	DRG-315L1-4
160 kW – 3,000 rpm	—	DRG-315L1-2
200 kW – 1,000 rpm	DRG-355M2-6	—
200 kW – 1,500 rpm	—	DRG-315L2-4
200 kW – 3,000 rpm	—	DRG-315L2-2
250 kW – 3,000 rpm	DRG-355M-2	—
250 kW – 1,500 rpm	DRG-355M-4	—
250 kW – 1,000 rpm	DRG-355L-6	—
355 kW – 3,000 rpm	—	DRG-400M-2
355 kW – 1,500 rpm	—	DRG-400M-4
355 kW – 1,000 rpm	—	DRG-400L-6

In practice, when a request says "250 kW motor", we ask for the pole count first and the frame second. The DRG-355M-4 and the DRG-355L-6 have the same power but different foot spacing and torque (1,602 / 2,412 Nm). The 315 frame counterparts are listed frame by frame in the price list by frame number.

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Shaft: 75×140 mm on 2-pole, 100×170 mm on 4/6-pole

On 355M and 355L, the shaft size is set by the pole count, not by the frame. The DRG-355M-2 and DRG-355L-2 have a 75×140 mm shaft with a 20 mm key; all six 4/6-pole models use a 100×170 mm shaft with a 25 mm key. Shaft diameter grows by 25 mm and shaft length by 30 mm; the 30 mm difference in overall length (L 1486 → 1516 mm) comes entirely from the shaft. Bearings follow the same split: 6319-C3 on 2-pole, 6322-C3 on 4/6-pole.

On site this difference shows up at the coupling. If a pump or fan is converted from 2-pole to 4-pole, the coupling hub bore changes from 75 mm to 100 mm even though the frame stays the same, and the machine needs room for a shaft 30 mm longer. See motor shaft diameter, key and coupling standards and the motor shaft diameter by kW table.

355M versus 355L: only B changes

In DRG product records, 355M and 355L share H 355, A 610, C 254, AC 698 and AD 642 mm. The dimension that changes is the lengthwise foot hole spacing B: 560 mm on 355M, 630 mm on 355L, a difference of 70 mm. The records also show the same overall length for both frames (L 1516 mm on 4/6-pole). The catalogue gives the foot holes as 6–Ø28. When preparing a base, compare the number and position of the holes with the existing base.

Dimension (mm)	355M – 2-pole	355M – 4/6-pole	355L – 4/6-pole
H – shaft height	355	355	355
A – foot hole spacing (across)	610	610	610
B – foot hole spacing (lengthwise)	560	560	630
C – shaft shoulder to foot hole	254	254	254
K – foot holes	6–Ø28	6–Ø28	6–Ø28
D – shaft diameter	75	100	100
E – shaft length	140	170	170
F – key width	20	25	25
AC – housing diameter	698	698	698
AD – axis to terminal box top	642	642	642
L – overall length	1486	1516	1516

The 6-pole 355M1, 355M and 355M2 share the column of the 4-pole 355M; the 2-pole 355L matches the 2-pole 355M column except for B. Drawing files are on the 2D technical drawings and 3D technical drawings pages; mounting arrangements are compared in motor mounting types B3, B5, B14 and B35.

B5 flange dimensions and a note on B14

DRG's B5 large-flange catalogue table has two rows each for 355M and 355L: 2-pole and 4/6/8/10-pole. The M and L rows are identical, so they are merged below. The flange itself does not change with pole count: outer diameter P 800 mm, spigot diameter N 680 mm, bolt circle M 740 mm, hole diameter S 24 mm, spigot depth T 6 mm, flange thickness LA 25 mm.

B5 dimension (mm)	355M / 355L – 2-pole	355M / 355L – 4/6/8/10-pole
P – flange outer diameter	800	800
N – spigot (pilot) diameter	680	680
M – bolt circle diameter	740	740
S – flange hole diameter	24	24
T – spigot depth	6	6
LA – flange thickness	25	25
D×E – shaft	75×140	100×170
F – key width	20	25
G – shaft to key-seat bottom	67.5	86
DH – shaft end thread	M20×42	M24×50
LB – flange face to rear end	1346	1346
L – overall length	1486	1516
KK – cable entry	2–M63×1.5	2–M63×1.5

Although the flange stays the same, the shaft end thread changes (M20×42 / M24×50); keep this in mind if a coupling or shaft puller is being prepared. Values for every frame are in the B5 motor flange dimensions table, and the FF flange is explained in B5 and B14 flange FF/FT difference. The B14 small-flange table is not part of the DRG catalogue, so we do not give B14 or B34 dimensions for the 355 frame; if you need such a connection, send the flange outer diameter, bolt circle, spigot diameter and thread size on WhatsApp and we will check it.

Current at 400 V, torque and the 2–M63×1.5 cable entry

Currents at 400 V on this frame range from 281 A to 526 A; all models have 400/690 V (Δ/Y) connection. Torque values come from DRG records; the last column is our check with M = 9550·P/n (P in kW, n = nameplate speed).

Model	Current at 400 V (A)	Rated torque (Nm)	Check: 9550·P/n
DRG-355M1-6	281	1,543	9550·160/990 = 1543.4
DRG-355M-6	not in record	not in record	not in record
DRG-355M2-6	346	1,929	9550·200/990 = 1929.3
DRG-355M-2	414	800.6	9550·250/2982 = 800.6
DRG-355M-4	418	1,602	9550·250/1490 = 1602.3
DRG-355L-6	433	2,412	9550·250/990 = 2411.6
DRG-355L-2	522	1,009	9550·315/2982 = 1008.8
DRG-355L-4	526	2,019	9550·315/1490 = 2,019

The highest rated torque belongs to the DRG-355L-6 (2,412 Nm), while at the same 250 kW the 2-pole DRG-355M-2 delivers only 800.6 Nm — which is why the thinner shaft is sufficient. The terminal box has two cable entries (2 × M63×1.5); at these currents, plan cable size and glands together. Use the motor current chart, the motor cable size calculator and the electric motor calculator.

Ordering information: seven data points for a replacement

On a 355 frame, a wrong order costs far more than on small frames because of the motor's weight and transport to site. With the seven items below complete, the model choice is usually settled in a single conversation.

Information to send	Where to read / measure it	Value in the 355 data
Power and rated speed	Existing motor nameplate	160, 185, 200, 250, 315 kW; ~2,982 / ~1,490 / ~990 rpm
Frame code and sub-code	Type line on the nameplate (355M1, 355M, 355M2, 355L)	on 6-pole the power is read from the sub-code
Shaft diameter × length, key	Caliper; length from shoulder to end; keyway width	75×140 mm / F 20 (2-pole) — 100×170 mm / F 25 (4/6-pole)
Foot holes	Hole centres across (A) and lengthwise (B)	A 610; B 560 (355M) / 630 (355L); 6–Ø28
Shaft height	From base surface to shaft axis	H 355 mm
B5 flange (if any)	Outer diameter, spigot, bolt circle, hole size	P 800 / N 680 / M 740 / S 24 mm
Cable entry and connection	Terminal box gland holes, nameplate voltage	2 × M63×1.5; 400/690 V (Δ/Y)

If the nameplate is unreadable, the shaft diameter is a quick separator: on the 355 frame, a 75 mm shaft appears in DRG data only on the 2-pole models. The general ordering steps are listed in the motor frame size order guide.

Frequently asked questions

Is there a dimensional difference between 355M2 and 355M?

Not in DRG product records. The DRG-355M2-6, DRG-355M-6 and DRG-355M1-6 share the same B3 dimensions and the 100×170 mm shaft; they differ in power (200 / 185 / 160 kW).

Can a 355L motor replace a 355M motor?

Shaft height (355 mm), transverse spacing (610 mm) and the shaft for the same pole count stay the same, but the lengthwise foot spacing rises from 560 mm to 630 mm. Base holes and terminal box orientation must be checked separately.

Do 315 kW 2-pole and 315 kW 4-pole motors use the same shaft?

No. Both are 355L, but the DRG-355L-2 has a 75×140 mm shaft and the DRG-355L-4 a 100×170 mm shaft; key widths are 20 and 25 mm.

Is a 355 kW motor on the 355 frame?

No. At DRG the top rating on the 355 frame is 315 kW; the 355 kW models are on 400L / 400M. In a frame code, "355" is the shaft height in mm, not the power.

Technical confirmation

DRG Motor is an electric motor manufacturer, supplier and seller. To pick the right 355 model, send us a photo of the existing nameplate together with the shaft diameter and length, the B dimension or the flange dimensions. For the general design of large cast iron frames see cast iron frame and high kW motors and the DRG technical and product catalogue.

Send a photo of your current motor nameplate and we will find the suitable DRG model together.Send on WhatsApp

Browse the 160–315 kW motors on the 355M and 355L frames and their current pricesSEE PRICES

Electric Motors Related to This Topic — Models and Current Prices

Suitability is not decided by power alone: compare the speed, voltage, mounting, shaft and fixing dimensions of your machine with the product data; if unsure, send us the nameplate of your current motor.