Overload Underload Motor Protection Relay

General

Applications

Electronic motor protection relay special used in switchgear,air conditeoning units,elevator machine room, pumps, fans and other motor control applications, With phase loss,overload and so on multi protect function automatically.

Features

Under current protection relay Built-in microcontrollers, current measurement accuracy≤0.2%. Konb setting,LED indicator shows working status. With phase failure, overload, unbalance, stall protection, four optional trip classes. No-load start, protection of any phase loss or overload. NO contact protection.

Electronic overcurrent relay Model Description

AC current relay Model Selection Table

100 amp 240v relay Technical Parameters

Wiring Diagram

Dimensions(mm)

Ordering instructions

ZHRA2-60/A220

Model significance:

ZHRA2-S 60/A220 motor protector, button setting, setting current range 5A~60A, rated control voltage AC220V.Simple mini design, multi protect function, widely working range, long working life with 18 months warranty,OEM and ODM service,quality product with good cost for AC power system.

Welcome your kindly enquiry to discuss more.

OPERATION

When power is applied through the cycling control, both the run (main) winding and the relay coil see locked rotor current because they are in series with one another. The start winding cannot experience any current flow because of the normally opened contacts of the relay being wired in series with it.

Because both run winding and relay coil experience locked rotor current, the relay coil will form a strong electromagnetic field around it from the high locked rotor current draw of the run winding. Because the relay coil has a very low resistance (usually under 1 ohm), it will not be a large power consumer to interfere with the run winding's power consumption needs. The strong electromagnetic field formed around the relay's coil will make it an electromagnet. This is caused from the iron core that the relay coil is wrapped around. This magnetism is the force that will close the normally open contacts in series with the start winding and start capacitor. The motor's rotor now starts to turn.

Once the start winding is closed, the motor will quickly accelerate in speed. Once the motor has reached about three-fourths of its rated speed, the current draw of the run winding will decrease from a counter electromagnetic force (CEMF) on it. It is this reduced flow that will decrease the electromagnetic force in the iron core the relay coil is wrapped around. Now, spring pressure or gravity forces the contacts between (L and 2) or (L and S) back to their normally opened position.

On capacitor start motors, this action takes both the start capacitor and start winding out of the circuit. On capacitor start-capacitor run motors, the action only takes the start capacitor out of the circuit. The start winding will be left in the circuit by the run capacitor's wiring. But line power will not be directly applied to the start winding.

The run capacitor will help with the running torque and also limit the current draw through the start winding while the motor is in the running mode. This configuration makes the motor a permanent split capacitance (PSC) motor only while running.