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How to determine the resistance of a CA7 Contactor Coil

Question: What is the resistance on my contactor coil?

Answer: With an Ohm meter, the contactor coil resistance can be measured using the A1-A2 terminals of the coil. But how do you know if the measurement is correct? In a troubleshooting situation it may be necessary to measure the coil resistance from the contactor coil. When measuring this resistance, a zero (a short circuit) or an infinity (an open circuit) is not what you want to see on your meter.

The resistance charts below for Series CA7 Contactors are not printed in the Sprecher & Schuh catalog, but may be helpful in these troubleshooting situations. If the coil resistance does not meet these specifications, there may be a connection or other problem. Contact technical support for assistance.

• AC Coil Data for CA7 Contactors 9A...97A

Coil Resistance in Ohms
Volts			Coil Code	CA7-9..16		CA7-23..37		CA7-43..55		CA7-60...85		CA7-90...97
50 Hz	60 Hz	50/60 HZ		Coil No.	Ohms	Coil No.	Ohms	Coil No	Ohms	Coil No	Ohms	Coil No	Ohms
~	12V	~	12B	TA006	1.08	TC006	0.76	TD006	0.55	TE006	0.27	TF006	0.20
12V	14V	~	12A	TA404	1.35	TC404	1.09	TD404	0.82	TE404	0.37	TF404	0.27
~	24V	~	24B	TA013	4.55	TC013	3.06	TD013	2.24	TE013	1.02	TF013	0.75
24V	~	~	24A	TA407	5.05	TC407	3.56	TD407	3.21	TE407	1.48	TF407	1.05
~	~	24V	24Z	TA855	4.65	TC855	3.35	TD855	2.5	TE855	1.33	TF855	0.75
32V	36V	~	36	TA481	10.71	TC481	7.32	TD481	5.49	TE481	2.47	TF481	1.79
36V	42V	~	36A	TA410	12.35	TC410	8.36	TD410	7.71	TE410	3.57	TF410	2.30
42V	48V	~	48	TA482	17.57	TC482	12.38	TD482	8.87	TE482	4.26	TF482	3.13
48V	55V		48A	TA414	20.59	TC414	14.23	TD414	12.85	TE414	5.95	TF414	4.19
~	~	48V	48Z	TA860	19.05	TC860	13.46	TD860	9.63	TE860	4.47	TF860	3.13
100V	100..110V	100	110	TA861	79.56	TC861	55.84	TD861	51.59	TE861	22.51	TF861	14.97
110V	120V	~	120	TA473	115.9	TC473	83.09	TD473	60.67	TE473	26.8	TF473	19.08
~	~	110V	110Z	TA856	106.8	TC856	76.49	TD856	57.95	TE856	25.35	TF856	16.91
120V	130V	~	120A	TA425	128.41	TC425	110.81	TD425	81.07	TE425	37.81	TF425	24.66
127V	~	~	127A	TA428	163.79	TC428	118.19	TD428	85.76	TE428	38.74	TF428	24.66
200V	200.. 220V	200V	220	TA862	351.28	TC862	300.64	TD862	220.42	TE862	92.62	TF862	68.17
180V	208V	~	208	TA049	303.9	TC049	258.21	TD049	188.77	TE049	91.66	TF049	55.71
200..220V	208.. 240V	~	220W	TA296	370.79	TC296	285.19	TD296	218.02	TE296	98.76	TF296	147.32
220V	240V	~	240	TA474	480.42	TC474	367.18	TD474	287.51	TE474	112.23	TF474	77.93
220..230V	260V	~	230A	TA441	507.87	TC441	367.18	TD441	295.76	TE441	115.48	TF441	89.06
~	~	230V	230Z	TA851	464.17	TC851	356.69	TD851	287.51	TE851	109.02	TF851	73.29
230..240V	~	~	240A	TA440	512.34	TC440	391.79	TD440	306.7	TE440	115.48	TF440	89.06
240V	277V	~	277	TA480	637.11	TC480	404.23	TD480	327.48	TE480	150.7	TF480	97.13
~	~	240V	240Z	TA858	494.03	TC858	377.77	TD858	302.27	TE858	115.48	TF858	77.93
~	347V	~	347	TA065	999.43	TC065	719.19	TD065	540.06	TE065	239.92	TF065	153.16
330V	380V	~	380B	TA067	1118	TC067	805.65	TD067	592.21	TE067	268.45	TF067	188.71
380V..400V	440V	~	380	TA071	1692.5	TC071	1172	TD071	852.36	TE071	379.97	TF071	270.09
~	~	400V	400Z	TA863	1566.7	TC863	1116.9	TD863	841.53	TE863	362.17	TF863	227.71
400V..415V	~	~	415	TA457	1692.5	TC457	1213	TD457	882.07	TE457	398.04	TF457	277.01
440V	480V	~	480	TA475	1895.3	TC475	1624	TD475	1177.1	TE475	413.41	TF475	294.53
~	~	440V	440Z	TA859	1757.8	TC859	1263.4	TD859	1122.3	TE859	402.84	TF859	277.01
500V	575V	~	500A	TA479	2639.9	TC479	1906.6	TD479	1408.8	TE479	627.96	TF479	446.71
550V	600V	~	600	TA476	3642.4	TC476	2581.7	TD476	1855	TE476	659.1	TF476	406.63

• DC Electronic Coil Data for CA7 Contactors 9A...55A at 110-125V DC

For Electronic DC Contactors CA7-9E..55E, the input power (current) is controlled and adjusted by an electronic circuit. The input impedance (A1-A2) of the electronic coil (110-125VDC) is dependent on the input voltage, on the pick-up or holding phase, and on the frame size of the contactor. These resistance measurements vary during pick-up and are constant during hold-in. The varying pick-up values are created by an input impedance, and this makes it difficult to determine.

• DC Coil Data for CA7 Contactors 60A...97A Two Winding DC

Coil resistance is stated in ohms. For coils used with CA7-60D thru CA7-97D contactors, the coil resistance value is measured when the coil is in its shelf state (de-energized). The coils used with CA7-60 thru CA7-97 contactors use a 'two-stage' coil that has two windings instead of one. The coil resistance, when the coil is fully energized, will be much higher because both windings will be pulled into the coil circuit.

Coil Resistance in Ohms
Volts DC	Coil Code	CA7-60D..85D		CA7-90D..97D
W/ Diode		Coil No.	Ohms	Coil No.	Ohms
9V	9DD	TE766M	0.28	TF766M	0.23
12V	12DD	TE708M	0.51	TF708M	0.45
24V	24DD	TE714M	2.27	TF714M	1.82
36V	36DD	TE719M	5.13	TF719M	3.73
48V	48DD	TE724M	764.8	TF724M	7.20
60V	60DD	TE774M	14.91	TF774M	11.15
64V	64DD	TE727M	14.91	TF727M	11.15
72V	72DD	TE728M	23.48	TF728M	14.22
80V	80DD	TE729M	23.48	TF729M	14.22
110V	110DD	TE733M	51.69	TF733M	36.68
115V	115DD	TE734M	51.69	TF734M	36.68
125V	125DD	TE737M	66.73	TF737M	44.23
220V	220DD	TE747M	200.29	TF747M	141.14
230V	230DS	TE749M	200.29	TF749F	141.14
250V	250DS	TE751M	259.89	TF751F	174.49

• DC Coil Data for CA7 Contactors 9A...43A True DC (discontinued)

		Coil Resistance in Ohms
Volts DC	Coil Code	CA7-9C..16C(D)		CA7-23C..37C(D)		CA7-40C..43C(D)
DC		Coil No.	Ohms	Coil No.	Ohms	Coil No.	Ohms
9V	9D	TA766	10.53	TC766	8.6	TD766	9.3
12V	12D	TA708	21.3	TC708	15.9	TD708	16.6
24V	24D	TA714	67.5	TC714	62.6	TD714	57
24V Diode	24DD	TA714M	67.5	TC714M	62.6	TD714M	57
36V	36D	TA719	169	TC719	133.2	TD719	145.3
48V	48D	TA724	322.9	TC724	249.5	TD724	225.1
60V	60D	TA774	506	TC774	397.1	TD774	360
64V	64D	TA727	506	TC727	397.1	TD727	360
72V	72D	TA728	608.7	TC728	589.7	TD728	565
80V	80D	TA729	790.3	TC729	589.7	TD729	565
110V	110D	TA733	1670.7	TC733	1212.8	TD733	1040
115 V	115D	TA734	1670.7	TC734	1212.8	TD734	1040
125V	125D	TA737	2076.4	TC737	1528.4	TD737	1552
220V	220D	TA747	5939.3	TC747	4823	TD747	4357
230V	230D	TA749	7554.6	TC749	4823	TD749	4357
250V	250D	TA751	7554.6	TC751	7004	T E751	6337