PSV691U line protection device of Guodian Nanzi microcomputer protection device
1 Function
Two section low-voltage protection
Bus insulation detection
Phase voltage, line voltage, zero sequence voltage, 10 circuits switch Quantity acquisition
GPS time synchronization (minute pulse, second pulse or IRIG-B mode)
2 Principle description
2.1 The device collects four line voltages Uab, Ubc, Uca, Uac 'and one zero sequence voltage. Uac 'is 5RD
The voltage circuit is only used for this device and does not lead to the voltage bus, so the possibility of short circuit in Uac 'circuit is very small.
2.2 Two section low-voltage protection
When the voltage of the four lines is less than the fixed value, the device will close the outlet connector after a time delay to trip the corresponding Motor or transformer 。 Low voltage I
Section delay is generally set as 0.5S to trip Class II and III motors (at Power Supply After the voltage disappears for a long time, it must be removed from the power network
Automatic disconnection). Low voltage two-stage delay is generally set as 9S, which is used to trip Class I motor (do not require self starting motor and non self starting motor
Motor).
2.3 Bus insulation detection
When the zero sequence voltage (3U0) is greater than the fixed value, the device sends a signal after a delay.
2.4 PT disconnection function
PT disconnection sends alarm signal and locks low-voltage protection.
If the voltage difference between the larger voltage and the smaller voltage of the four lines is greater than 30V and the delay is 3 seconds, the PT is considered to be disconnected.
If Uab is greater than 30V and the voltage difference between the four lines is smaller than 30V, PT will return after disconnection.
2.5 PT disconnection function
The device shall be connected to the PT trolley position node (normally open). The low-voltage protection is locked when the PT trolley position node is disconnected.
2.6 Use method of low-voltage protection
Lead low-voltage outlet node to external tripping of motor protection operation circuit. Although there is low-voltage protection in motor protection
It is recommended to use this protection, because the possibility of Uac 'circuit fault of this protection is very small, so the possibility of low-voltage maloperation is very small. And on-site operation
When overhauling PT, pulling out PT trolley directly will not cause low-voltage maloperation.
