GAMA Electronics polarity reversing control modules lead the market in safety, economy and flexibility. For DC or AC reversing applications, you will find our controllers a smart and convenient solution that can be added to an existing system or easily integrated into your product design.
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Remote Control Anyone?
Add another dimension to your polarity reversing control application: Remote control. By using remote control of DC motors and other loads you can gain a cost advantage when long distance control wiring is the alternative. Remote control is an option when retrofitting an existing system when new wiring would interfere with an on-going process or even to improve certain safety aspects of an operation. Our controllers can quickly install in places that would otherwise be inaccessible or inappropriate. Operators with the ability to control systems from a remote location have a safety advantage. Visibility can be impaired when the operator has to work from a fixed control location. In many cases, being able to move around a large workload without being tethered to the control panel results in a safer environment for the operator and for the material being handled.
Just how safe is RF remote control for commercial and industrial applications? You might think that a remote control is okay for television, but not for the applications you deal with. In some cases this is absolutely true. As with any control system, risk assessment is the determining factor. High risk situations must be given careful consideration before implementing any control strategy, but the more common fault conditions related to remote controls have been eliminated, or at least reduced by the use of intelligent features included in our transmitters and receivers.
The following diagram show a typical polarity reversing, two-relay system. In its normally-off state both M1 and M2 output terminals are connected to DC supply NEG 12V. This results in zero rotation. If either of the control outputs from the receiver/control is on, the corresponding relay coil is energized. In one case, M1 output terminal receives POS 12V while M2 remains at NEG 12V. For operation in the other direction, M2 output terminal receives POS 12V while M1 remains at NEG 12V.
The receiver contains circuits that engage and disengage the contacts of a set of two output relays. The relay contacts default to a fail-safe condition (regardless of how the load has been connected). In order for a 2-wire DC motor to energize, one wire must be positive with respect to the other, and the circuit must have the current carrying capacity to deliver the electrical power required. If both wires are at the same electrical potential - either positive or negative - no current will flow in the motor circuit. The output relays in our polarity reversing remote control receivers are designed so that in the case of power or communication failure, both motor leads will revert to the same potential causing zero motor rotation. Receiver outputs will remain in the energized state for about 130 milliseconds after the last valid control signal is received. Possible causes of receiver unintentionally energizing relay: Mechanical failure of key fob transmitter button (stuck). Short circuit in key fob switch.
RF Receiver Security
Each transmitter has its own unique internal address that is transmitted when a button is pressed. The receiver is paired with the transmitters you select and will respond only to them. A high level of security is possible owing to the 1,048,576 unique addresses available in each transmitter. To activate the receiver outputs, the paired transmitter continuously transmits its address along with the data bits identifying the button pressed. Each message is 61 ms long. If a valid control signal is not received within 200mS, ALL outputs are de-energized.
Manual switch inputs
The UP/DOWN manual inputs connect directly to the output relay coils. These relay coils have a DC resistance of about 85 ohms. Typically these relays will energize at 6 to 8 VDC and drop out 2.5 to 3.5 VDC.
DC Motor Polarity Reversing Controls
Bipolar DC control is found in applications such as industrial doors, gates, conveyor systems, process controls, hoists and winches, multi-axis positioning, general robotic functions and land and marine transportation. Permanent magnet DC motors and actuators are highly efficient, with excellent torque and holding power. DC systems perform adequately, and economically, incorporating only start-stop and directional control with limit switch feedback. GAMA Electronics stocks both RF remote controls and simple switches for this purpose.
AC Motor Reversing Controls
In addition to our line of DC Polarity Reversing controls, we also offer several products capable of changing the direction of a single phase AC motor. Reversible AC motors are found in industrial and consumer applications such as fans and garage door openers. The two most common reversible motor types are referred to as three-wire and four-wire. The three-wire motors simply have one winding for forward and one for reverse. Possibly the more common means is to use a a small start winding that gives the motor a nudge in the desired direction of rotation. Once the motor is up to speed, the start winding is switched out of the circuit and the motor continues rotation in the direction it was started. GAMA Electronics has remote controls capable of reversing both types of motors.
GAMA Electronics' RF120VPR1L and RF240VPR1L radio remote controls are ideally suited for applications requiring control of 4 wire reversible single phase AC motors. In addition, the lower cost RF120V-2WP and RF240V-2WP radio remotes are suitable for use with three-wire reversible AC motors constructed with dual windings. Examples of 3-wire motors are found in window and door actuators, process controls, and combustion vent and feed water valve actuators.
3 Wire Systems
The simplest reversing single phase AC motors use a 3-wire configuration. In this case, there are two separate motor windings; one for each direction. Controlling direction of rotation is a matter of energizing winding A or winding B. Our RF120V-2WP, LRF120V-2WP and RF240V-2WP remote controls are appropriate for this application.
4 Wire Systems
In a 4-wire system, the starting circuit contains a centrifugal switch, start capacitor and start winding in the motor. Standard wiring for this circuit terminates at wire numbers 5 and 8. Normally, the two wires for the motor's main winding are labeled 1 or L1 and 4 or L2. They are the main power leads. Note: If the start circuit is not connected, or if the start capacitor fails, the motor will hum or vibrate, but will not turn. This is a common failure mode for four wire single phase AC motors.
If wires 5 and 1 are connected and wires 8 and 4 are connected, rotation will be in the counter-clockwise direction. If wires 5 and 4 are connected and wires 8 and 1 are connected, rotation will be in the clockwise direction. Our newest AC reversing controls, the RF120VPR1L and 240VPR1L are perfectly matched to this application.