Overtemperature protection and thermistors
As a standard, HDD motors are equipped with overtemperature protection. The protection consists of three PTC thermistors in series, one for each phase. The PTC thermistors are manufactured according to norms DIN 44081 and DIN 44082. According to these norms, the resistance for a single thermistor at room temperature is in the range 20 Ohms – 250 Ohms. For three thermistors in series, the total room temperature resistance is typically between 150 Ohms – 300 Ohms (50 Ohms – 100 Ohms per thermistor), but can be as high as 750 Ohm without indicating malfunction.
The PTC thermistors have a switch temperature of 150 C. When T < 145 C, R < 550 Ohm for each thermistor (R < 1650 Ohms for the whole triplet), and when T > 155 C, R > 1330 Ohm for each thermistor (R < 4990 Ohms for the whole triplet). The resistance should be measured with a d.c. voltage no greater than 2.5V. More detailed information about the PTC resistors can be found here.
As an option, HDD motors can be equipped with a temperature measurement device of type KTY84-130. Detailed information about this device can be found here. The resistance of the KTY device depends continuously on temperature, as described in this document.
Available feedback alternatives
Name | Type | Description | Information | Data sheet |
A | Resolver | 7 V input, 1 pole pair, 0.5 transf. ratio | Data sheet | |
D | Resolver | 9 V input, 1 pole pair, 0.3 transf. ratio | Data sheet | |
EC | Endat 2.1 singleturn | 32 lines (19 bits) per rev. | ECI 119 | Data sheet |
ED | Endat 2.2 singleturn | 32 lines (19 bits) per rev. | EBI 135 | Data sheet |
EE | Endat 2.2 singleturn, SIL2 | 25 bits per rev. | ECN 1325 | Data sheet |
EF | Endat 2.2 multiturn, SIL2 | 25 bits per rev. | ECN 1337 | Data sheet |
EH | Endat 2.2 | 32 lines (19 bits) per rev. | ECI 119 | Data sheet |
EM | Endat 2.1 multiturn | 512 lines per rev. | EQN 1325 | Data sheet |
EN | Endat 2.1 multiturn | 2048 lines per rev. | EQN 1325 | Data sheet |
EO | Sincos, commutation signal | 2048 lines per rev. | ERN 1387 | Data sheet |
EP | Endat 2.2 battery buffered multiturn | 18 bits per rev. | EBI 1135 | Data sheet |
EQ | Endat 2.1 singleturn | 18 bits per rev. | ECI 1118 | Data sheet |
ES | Endat 2.1 singleturn | 512 lines per rev. | ECN 1313 | Data sheet |
ET | Endat 2.1 singleturn | 2048 lines per rev. | ECN 1313 | Data sheet |
EV | Endat 2.2 singleturn | 19 bits per rev. | ECI 1319 | Data sheet |
EW | Endat 2.2 multiturn | 19 bits per rev. | EQI 1331 | Data sheet |
EY | Endat 2.2 singleturn | 18 bits per rev. | ECI 1118 | Data sheet |
SS | Hiperface Sincos singleturn | 1024 lines per rev. | Electrically equivalent to SRS50 | Data sheet |
SM | Hiperface Sincos multiturn | 1024 lines per rev. | Electrically equivalent to SRM50 | Data sheet |
SC | Hiperface Sincos singleturn 50mm hollow shaft | 64 lines per rev. | Electrically equivalent to SEK90 | Data sheet |