- Electric motor connection
- Starting equipment
- Pushbutton posts and limit switches
- Gate control via frequency converter
- Frequency converter setting principle
- Setting the door braking using a frequency converter
In this part of the sliding gate installation guide, you will learn how to assemble an electrical control circuit with your own hands. We will tell you how to connect different types of motors and assemble starting equipment, as well as reveal the secrets of smooth starting and stopping of automatic sliding gates..
Depending on the selected motor type, you can use different connection methods. Not only the wiring diagram will differ, but also the permissible current parameters.
Attention! When working with the electrical part, do not forget about the safety measures: weld the bolt to the stationary frame that will be used to connect to the ground loop.
Electric motor connection
A three-phase motor with a rated voltage of 380/220 V must have a star connection when connected to a three-phase power supply. You can change the direction of rotation by swapping the connection of any two of the three phases.
If you are trying to connect a three-phase motor to a single-phase network, give preference to the capacitive method. At the same time, use a starting capacitor of a knowingly high capacity (2-3 times) and add a pair of compensating capacitors for the two remaining windings to the working assembly, or provide for disconnecting the starting capacitor using a time relay. The capacity of the working capacitor is selected at the rate of 70-80 μF per 1 kW of power, and the nominal value is 450 V.
A single-phase capacitor motor has four wires in the assembly, that is, two ends of the starting and working windings. The standard terminal block pin markings are:
- Terminals U1 and U2 (or B1 and B2) – main winding.
- Terminals W2 and V2 (or C1 and C2) – starting winding.
- Terminals V2 and V1 – starting capacitor.
The connection of the starting winding remains constant, while the polarity of the power supply of the working winding can be reversed to change the direction of rotation.
Note:polarity is determined by the position of jumpers on the motor terminal strip, which will be closed remotely via the contactor.
To assemble the electrical circuit, you will need two IEK KMI 1121 magnetic starters with a 230 V coil supply voltage, or one PML 2561 reversing starter (the advantage of the latter is the presence of a mechanical interlock). There should be three main contacts.
It is also necessary to have an auxiliary contact block, which includes one normally open and one normally closed contact. Additionally, you will need a button housing IEK KP103 with three buttons “Start”, “Reverse” and “Stop”. To install the post from the street side, it is recommended to complete it with buttons with a turnkey lock. All switching electrical equipment must be mounted in a metal box with a degree of protection IP54 and gland entries for wires.
Connect the input contacts of the two starters in parallel, applying phase and zero to them from the 220 V network through the circuit breaker. On the back of the starters, connect the two power wires of the starting winding.
Using the AIRE 80 motor as an example, the power must be supplied to terminals V1 and W2. Note that the polarity remains the same regardless of which starter is turned on. Terminals U1 and U2 belong to the ends of the working winding and must be connected to two starters in a different sequence.
The coils of each starter must be powered through the second starter’s own normally open and normally closed contacts. This will provide self-catching and holding the coil in the on state, as well as provide an electrical interlock of the opposite start..
Pushbutton posts and limit switches
The drive is controlled by one or several push-button posts. The phase wire is passed through the series-connected normally closed contacts of the “Stop” buttons, which is necessary for the possibility of breaking the coil holding circuit from any button.
Then the power is supplied to the normally closed contacts of the Start and Reverse buttons, then from the terminals of each button power is supplied to the normally open opposite pair. These contacts control the activation of the coils of the respective starters. Crossover connection through break contacts is necessary to avoid unintentional back-to-back connection of starters.
In order for the drive to switch off on its own and in a timely manner when the gate reaches the extreme points of opening and closing, the electrical circuit must be supplemented with limit switches. VPK-2112 or ME 8104 switches with one normally closed contact are suitable. It is recommended to use products equipped with a roller.
The limit switches must be rigidly fixed to the stationary door frame so that the roller is 1–2 mm from any longitudinal door element. It can be a supporting frame or a rail, the main thing is that the side surface is absolutely flat. The gate must be put first in the open, then in the closed position and mark the points of contact with the rollers.
Note!Since massive gates continue to move by inertia, it is recommended to shift the marks a few centimeters in the opposite direction so that the limit switch is triggered with a little advance.
According to the marked marks, you need to weld on small protrusions, the height of which will be sufficient for the confident operation of the switch. It is also important that the mark is long enough to hold the roller, and not slip over it, briefly activating the limit switch. The switch must be in the trip position until it starts moving in the opposite direction, when it leaves the mark and closes the circuit again.
The electrical connection of the limit switches can be done in two ways.
Connection diagram of push-button posts and limit switches
Method number 1.The normally closed contacts are wired in series and included in the contactor coil holding circuit. The switch-on location is between the series-connected Stop buttons and the normally open contacts of the starters. The disadvantage of this method is that when the gate is turned on, it takes a certain amount of time to keep the button pressed until the switch leaves the trip position..
Method number 2.It implies the independent inclusion of limit switches in the coil holding circuit of each starter. The normally closed switch contact is located between the normally open auxiliary contact of the starter and the coil terminal. It is also allowed to put the switch in the electrical interlocking circuit: between the coil of one and the normally closed contact of the second starter. Thus, the switches work independently of each other, which means that no time delay is required when the drive is turned on..
Gate control via frequency converter
Since frequency converters have recently become more and more affordable and popular, it is appropriate to use them to control a gate drive, especially since there is more than one reason for this:
- Since the frequency converter supplies the drive with three-phase voltage, you save money by purchasing a more common motor with a lower power rating..
- Engine speed does not matter.
- Eliminated difficulties with connecting a three-phase motor.
- You avoid problems with starting the drive under load.
- The converter smoothly but quickly accelerates and stops the gate, opening occurs in a matter of seconds.
- No need to buy and install a reducer.
- No starter needed, simple wiring diagram.
- Engine life is significantly increased.
The average cost of a device with an output power of 2–2.5 kW is $ 250–300, so its purchase is fully justified, given the refusal to purchase a gearbox and starters.
Frequency converter CFM-240 is a budget option of the device, it also has the most common connection and control scheme. Following his example, you can easily deal with similar devices..
Frequency converter connection
Terminals L and N are used to supply, respectively, phase and zero from the 220 V network, it is important to observe the polarity here. Terminals U, V and W provide an output voltage for powering a 380/220 V three-phase asynchronous motor, the windings of which are delta-connected. The control is carried out by closing one of the control contacts DI1-DI3 to the common terminal GND. Accordingly, when DI1 and GND are closed, the motor starts, DI2 and GND will start the drive in the opposite direction, and DI3 and GND will stop it..
Frequency converter setting principle
The transducer is configured by changing the values of each of the 70 parameters. A full description of the functions and set values are indicated in the device passport. To correct the values, enter the parameter selection menu by pressing the “Mode” button until the display shows P —. Then you need to press “enter” and using the “up” and “down” arrows select the number of the desired parameter, press “enter” again, set the desired value and press “enter” again to save.
Using a frequency converter provides some additional possibilities. For example, you can use the positioning function by transmitting data from a door position sensor to the inverter. This will enable the device to be used in stepper motor mode. He will smoothly accelerate the gate and gently stop them at the extreme point, remembering both extreme positions of the canvas. It is a more convenient and advanced replacement for the limit switch system. It is only required to install a “quadrature encoder” type counter on the drive shaft.
The meter has two power supply wires connected to the + 12V and GND terminals, as well as two signal wires connected to the DI5 and DI6 terminals. The positioning function is activated by assigning the value “2” to parameter 60. Next, set the value “1” to parameter 61 to set the desired sensor type. Then, changing the values of parameters 62 and 63, determine the ratio between the number of pulses and the distance traveled.
For example, the motor shaft can move the gate by 25 cm per revolution, and the encoder attached to the shaft produces 200 pulses per revolution. This means that for every 1000 mm set in parameter 62 there will be 800 encoder pulses set in parameter 63.
Parameter 66 defines the type of braking, it must be assigned the value “1”. Parameter 67 defines the engine speed to which the maximum operating speed will be reduced, and the value of parameter 68 defines the required braking distance. Having configured the specified parameters, you can go to the main menu and indicate the distance that the gate must travel in millimeters. After completing the task, the counter will reset to zero and will be ready for a new cycle, counting in both directions.
The rated motor speed is set by the value of the output frequency (Hz) in the main menu of the program. You can change it in real time and increase it as long as the transmission mechanism remains stable. Also remember that too much acceleration will not allow the converter to effectively slow down at the end of the path. The acceleration time of the drive to maximum speed is set in seconds in parameter 10.
Setting the door braking using a frequency converter
Too massive doors require braking by the operator. To do this, the frequency converter has a function activated by parameter 21. The braking force and the time it takes to complete a stop are set by parameters 27 and 28 respectively. When braking the drive, load compensation must be used. To do this, power resistors with a resistance of at least 70 Ohm and a power of over 350 W must be connected to the power terminals Br (they can also be replaced with a bunch of 4-5 incandescent lamps connected in series).
Now you have several options for connecting the motor and you can choose the method that suits your needs. Each connection method can have a remote control scheme, which we will discuss in the next article..