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Sequence Three Phase Voltage Monitoring Relay 3A 250VAC Contact capacity
Phase sequence protector is a type of control relay that can
automatically identify the phase relay protection relay, to ensure
that some special mechanical and electrical equipment reversed due
to the power phase sequence reversed and cause accidents or
equipment damage. Such as elevators, central air conditioning,
cranes, motors, etc. If the phase sequence of the power supply is
wrong after repair, it will lead to accidents. The phase sequence
protector must be connected to the control circuit to ensure the
phase sequence is correct. Air-conditioner compressors also use
phase sequence protectors to ensure that the compressor will not be
reversed after maintenance.
working principle
Sampling three-phase power supply and processing, in the case of
phase sequence of the power supply phase sequence and protector
terminal input, the output relay is turned on, the device main
control circuit is connected. The existing two types of products
are: when the phase sequence of the power supply changes, the phase
sequence does not match, and the output relay cannot be turned on,
thereby protecting the equipment and avoiding the occurrence of
accidents; the other type uses digital micro-core technology
products and can realize automatic Phase sequence recognition, and
automatic phase sequence conversion, to ensure that the motor
rotates in a constant phase sequence.
The three-phase power supply is connected to the three connection
points U, V, W (some R, S, T or L1, L2, and L3) of the protector in
turn, and the auxiliary contacts of the phase sequence protector
generally have a normally open and normally closed state. In the
access control loop, it is connected normally or normally closed
according to the control principle or wiring diagram. When the
phase sequence is wrong or the phase is missing, the auxiliary
contact action of the protector is normally open, normally closed,
and normally closed. . If it plays a protective role, it should be
normally closed contacts.
Phase sequence protector temperature protection
When the motor of the phase sequence protector does not exceed the
rated value, the motor will overheat due to poor ventilation, high
ambient temperature, and frequent startup times. In this case, the
above over-current protection or overload protection cannot solve
the problem, so a thermal protector that directly reflects the
temperature change is needed.
Both temperature protection and overload protection use temperature to trigger protection, but not exactly the same. Overload protection is because the current exceeds the rated value for a long time to cause the relay to heat up and trigger protection; and the temperature protection is due to the poor heat dissipation, the overheating of the motor and the triggering of the protection. When temperature protection is triggered, the current value in the motor may be normal, so overload protection does not necessarily work. Temperature protection and overload protection can not be replaced with each other.
♦ Technical data
Type | JVM-A |
Measuring circuit | 220VAC,380VAC50/60Hz |
Monitoring functions | phase sequence,phase loss,overvoltage,undervoltage |
Voltage setting range | ±5%~±20% |
Trip delay time | 1-10s adjustable |
Indicators | Power,Normal |
Output contacts | 1 C/O |
Contact capacity | 3A,250VAC |
Dimensions(H*W*D) | 61*49*70mm |
Mounting | DIN rail |