Electric Motors - Torque vs. Power and Speed

Electric motor output power and torque vs. rotation speed.

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Work is the result of a force acting over some distance. Work is quantified in joules (Nm) or foot-pounds.
Torque is a rotating force produced by a motor’s crankshaft. The more torque the motor produces, the greater is its ability to perform work. Since torque is a vector acting in a direction it is commonly quantified by the units Nm or pound-feet.
Power is how rapidly work is accomplished - work in a given amount of time. Power is quantified in watts (J/s) or horse power.

Note that the driving force of an electric motor is torque - not horsepower. The torque is the twisting force that makes the motor running and the torque is active from 0% to 100% operating speed.

The power produced by the motor depends on the speed of the motor and is

zero at 0% speed, and
normally at it's top at operating speed

Note! - the full torque from zero speed is a major advantage for electric vehicles.

For full table - rotate the screen!

Power		Motor Speed (rpm)
		3450			2000			1750			1000			500
		Torque
hp	kW	(lb_f in)	(lb_f ft)	(Nm)	(lb_f in)	(lb_f ft)	(Nm)	(lb_f in)	(lb_f ft)	(Nm)	(lb_f in)	(lb_f ft)	(Nm)	(lb_f in)	(lb_f ft)	(Nm)
1	0.75	18	1.5	2.1	32	2.6	3.6	36	3.0	4.1	63	5.3	7.1	126	10.5	14.2
1.5	1.1	27	2.3	3.1	47	3.9	5.3	54	4.5	6.1	95	7.9	10.7	189	15.8	21.4
2	1.5	37	3.0	4.1	63	5.3	7.1	72	6.0	8.1	126	10.5	14.2	252	21.0	28.5
3	2.2	55	4.6	6.2	95	7.9	10.7	108	9.0	12	189	15.8	21.4	378	31.5	42.7
5	3.7	91	7.6	10	158	13.1	18	180	15	20	315	26.3	36	630	52.5	71
7.5	5.6	137	11	15	236	20	27	270	23	31	473	39	53	945	79	107
10	7.5	183	15	21	315	26	36	360	30	41	630	53	71	1260	105	142
15	11	274	23	31	473	39	53	540	45	61	945	79	107	1891	158	214
20	15	365	30	41	630	53	71	720	60	81	1260	105	142	2521	210	285
25	19	457	38	52	788	66	89	900	75	102	1576	131	178	3151	263	356
30	22	548	46	62	945	79	107	1080	90	122	1891	158	214	3781	315	427
40	30	731	61	83	1260	105	142	1441	120	163	2521	210	285	5042	420	570
50	37	913	76	103	1576	131	178	1801	150	204	3151	263	356	6302	525	712
60	45	1096	91	124	1891	158	214	2161	180	244	3781	315	427	7563	630	855
70	52	1279	107	145	2206	184	249	2521	210	285	4412	368	499	8823	735	997
80	60	1461	122	165	2521	210	285	2881	240	326	5042	420	570	10084	840	1140
90	67	1644	137	186	2836	236	321	3241	270	366	5672	473	641	11344	945	1282
100	75	1827	152	207	3151	263	356	3601	300	407	6302	525	712	12605	1050	1425
125	93	2283	190	258	3939	328	445	4502	375	509	7878	657	891	15756	1313	1781
150	112	2740	228	310	4727	394	534	5402	450	611	9454	788	1069	18907	1576	2137
175	131	3197	266	361	5515	460	623	6302	525	712	11029	919	1247	22058	1838	2494
200	149	3654	304	413	6302	525	712	7203	600	814	12605	1050	1425	25210	2101	2850
225	168	4110	343	465	7090	591	801	8103	675	916	14180	1182	1603	28361	2363	3206
250	187	4567	381	516	7878	657	891	9003	750	1018	15756	1313	1781	31512	2626	3562
275	205	5024	419	568	8666	722	980	9904	825	1120	17332	1444	1959	34663	2889	3918
300	224	5480	457	620	9454	788	1069	10804	900	1221	18907	1576	2137	37814	3151	4275
350	261	6394	533	723	11029	919	1247	12605	1050	1425	22058	1838	2494	44117	3676	4987
400	298	7307	609	826	12605	1050	1425	14405	1200	1628	25210	2101	2850	50419	4202	5699
450	336	8221	685	929	14180	1182	1603	16206	1351	1832	28361	2363	3206	56722	4727	6412
550	410	10047	837	1136	17332	1444	1959	19808	1651	2239	34663	2889	3918	69326	5777	7837
600	448	10961	913	1239	18907	1576	2137	21608	1801	2443	37814	3151	4275	75629	6302	8549

Electrical Motor Power, Velocity and Torque Equations

Torque in Imperial units can be calculated as

T_inlb = P_hp 63025 / n (1)

where

T_inlb = torque (in lb_f)

P_hp = horsepower delivered by the electric motor (hp)

n = revolution per minute (rpm)

Alternatively

T_ftlb = P_hp 5252 / n (1b)

where

T_ftlb = torque (lb_f ft)

1 ft lb_f = 1.356 Nm

Torque in SI units can be calculated as

T_Nm = P_W 9.549 / n (2)

where

T_Nm = torque (Nm)

P_W = power (watts)

n = revolution per minute (rpm)

Torque - Work done and Power transmitted

Electric Motor - Torque vs. Power and Speed

power (kW)

speed (rpm)

Load Calculator!

1 hp = 0.746 kW - power converter
1 lb ft = 1.355 Nm - torque converter

Electric Motor - Power vs. Torque and Speed

torque (Nm)

speed (rpm)

Load Calculator!

Electric Motor - Speed vs. Power and Torque

power (kW)

torque (Nm)

Load Calculator!

Example - Torque from an Electrical Motor

The torque delivered from an electrical motor producing 0.75 kW (750 W) at speed 2000 rpm can be calculated as

T = (750 W) 9.549 / (2000 rpm)

= 3.6 (Nm)

Example - Torque from an Electrical Motor

The torque delivered from an electrical motor producing 100 hp at speed 1000 rpm can be calculated as

T = (100 hp) 63025 / (1000 rpm)

= 6303 (lb_f in)

To convert to pound-force foot- divide the torque by 12.

Car engine torque

Electric Motors - Torque vs. Power and Speed

Electric motor output power and torque vs. rotation speed.

Electrical Motor Power, Velocity and Torque Equations

Electric Motor - Torque vs. Power and Speed

Electric Motor - Power vs. Torque and Speed

Electric Motor - Speed vs. Power and Torque

Example - Torque from an Electrical Motor

Example - Torque from an Electrical Motor

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