External Brake Resistor - AX2090-BW5x-xxxx

Appropriate use

The brake resistors from the AX2090-BW5x-xxxx series are exclusively designed for direct application with an AX5000 series servo drive or the AX5021 brake module. They are designed for installation as components in electrical installations and machines together with the servo drive or the brake module, and this is their only purpose.

Scope of supply

The scope of supply includes the following components:

• Brake resistor from the required performance class
• Technical documentation
• Packaging

If one of the components is damaged please notify the logistics company and Beckhoff Automation GmbH immediately.

Safety rules

The responsible staff must ensure that the application or use of the products described satisfy all the requirements for safety, including all the relevant laws, regulations and guidelines.

DANGER	Serious risk of injury through electric shock!
	Caution - Risk of injury through hot surfaces! Even when the AX5000 is disconnected from the mains voltage, dangerous voltage continues to be present at the "X02" terminals of the DC link for 5 minutes. Wait until the DC link capacitors are discharged before touching live terminals. The voltage measured between the DC+ and DC- terminals (X02) must have fallen below 50 V.

WARNING
	The temperature of the brake resistor housing surface may reach over 200 °C. Please ensure that the housing has cooled down below 40 °C before touching it.

	It is essential to observe chapter "Product overview-->Guidelines and Standards-->UL-Listing" if you wish to operate an AX5000 in an economic area that requires a UL-Listing.

Product description

Attention
	The brake resistor may only be connected to individual AX5000 devices or AX5021 brake modules. It must never be used in a drive system without the AX5021 brake module, since this may lead to its destruction through overload.

The external brake resistors of the AX2090-BW5x-xxxx series are able to convert the dynamic energy generated during braking of a servomotor into heat. The series covers a wide continuous power and peak power range. The built-in temperature switch enables the system to respond immediately to any overload of the brake resistor through analysis in the AX5000 or the PLC. All brake resistors of the AX2090-BW5x-xxxx series are UL and CSA approved.

Attention
	The built-in temperature switch must be monitored, so that the machine can be stopped in a controlled manner and switched off in the event of an overloading of the brake resistor.

Type key

Mechanical installation

Dimensions and technical data

*) 4% output reduction per 10 K temperature difference

Mounting positions and distances

(A) = vertical installation is only permitted according to the diagram (terminal box facing downwards).
(B) = horizontal installation

For all mounting positions the following minimum distances must be adhered to:

200 mm to adjacent components, walls etc. and 300 mm to components, ceilings etc. above. If the device is installed vertically (A), the minimum distance to components, floors etc. below is 200 mm in order to allow unobstructed flow of air to the brake resistor.

Electrical installation

DANGER

Disconnect the AX5000 from the mains before installing the brake resistor! Even when the AX5000 is disconnected from the mains voltage, dangerous voltage continues to be present at the "X02" terminals of the DC link for 5 minutes. Wait until the DC link capacitors are discharged before touching live terminals. The voltage measured between the DC+ and DC- terminals (X02) must have fallen below 50 V.

Remove the two screws (1) and remove the cover (2) in direction of the arrow. Connect an adequately dimensioned cable (see section Cables) to the terminals (3) of the resistor and the earthing stud (5) and take it out of the terminal box through the strain-relief assembly (9). Ensure adequate strain relief with the two screws (8). Connect the other side of the cable to the DC link contact connector X2 (10) of the AX5000. The connector is supplied with the AX5000. Connect the earthing cable to the earthing conductor of the control cabinet.

Connect an adequately dimensioned cable to the potential-free N/C contact (4) of the temperature switch and take it out of the terminal box through the strain-relief assembly (7) (see section Temperature switch). Ensure adequate strain relief with the nut (6).

Install the cover (2) in reverse order.

Cables

We recommend Beckhoff motor cables for connecting the brake resistors.

WARNING
	The brake resistors become very hot. Only use cables with adequate heat resistance.

Attention
	Use only shielded cables.

We recommend wire end sleeves.

Temperature switch

Attention
	The temperature switch is only used for temperature monitoring. The brake resistor is not switched off.

The temperature switch has a potential-free N/C contact, which enables immediate response to any overload of the brake resistor through analysis in the AX5000 or the PLC. Connect the cable directly to a free input of plug "X06". Then parameterise it such that the AX5000 stops the motor(s) with an emergency ramp or the PLC reads and processes this input.

Short-term capacity

Brake resistors are usually not operated continuously, but only exposed to short-time duty. In the following section the permitted short-term capacity is calculated based on the continuous power, overload factor and duty cycle.

Duty cycle

The duty cycle is a relative value that depends on the switch-on time (ton)and the cycle time. Cycle times up to 120 sec. are used directly in the calculation. Should the cycle time exceed 120 sec., the maximum relevant cycle time of 120 sec. is used in the calculation.

Example 1 ton = 60 s Cycle time = 280 s Duty cycle = 50 %

Example 2 ton = 40 s Cycle time = 180 s Duty cycle = 40 %

Overload factor

Calculation formula:

Short-term capacity = continuous power x overload factor

Overtemperature and continuous power at 100% duty cycle

If your application requires a higher continuous power than the specified nominal capacity, you can accept this state if a higher brake resistor temperature is permitted. The following diagram shows the overtemperature v. the continuous power.

Normal operating range, max. 130%: This operating range is recommended for maximum service life and error-free operation. Permitted operating range, max. 160%: This operating range is still permitted, although it results in shorter service life with higher failure probability. Inadmissible operating range, more than 160%: In this operating range there is a risk of destruction of the brake resistor through overheating. Due to the high temperatures the adjacent components are also at risk.

Attention
	Always ensure adequate ventilation of the brake resistor, since the temperatures of the housing surface may exceed 200 °C.