Use of Cookies

Cookies helping us to provide our service. If you continue browsing on this site, you agree that we may use cookies.

I agree

 FAQ brake resistor
 FAQ (frequently asked questions) Frequently asked questions answered concisely (Subject to change; Data without guarantee):
 Which KOCH resistor (single module) types are there?
 Which types of KOCH resistors (combinations) are there?
 What is a PTC brake resistor?
 What does KOCH mean by intrinsic safety?
 How does KOCH design?
 How does KOCH define the various terms and expressions used for electrical power?
 Why should you decide on KOCH resistors?
 Which resistance value tolerances does KOCH offer?
 How does the purchase process at KOCH work?
 Does KOCH also supply temperature monitoring for the resistors?
 Which assembly fittings does KOCH supply?
 What distinguishes a good brake resistor?

Which KOCH resistor (single module) types are there?
Wire-wound resistor types
- BWD = standard design, with wires ca. 540 mm long,
- BWG = with shielded cable, from 750 mm long (according to customer requirement),
- BWT = with terminal,
- BWS = with wires and flat pin bushing or other connectors (according to customer wish) and
- BWR = with converter-specific substructure frames (according to customer requirement).
PTC-based brake resistors are available as
- standard design,
- extra-flat profile or
- heat sink profile.
<<

Which types of KOCH resistors (combinations) are there?
We also supply so-called combinations consisting of several of our wire-wound resistors with and without electrical switching. The types are
1) with spacing bolts and fixing brackets (BWx...K...),
2) as BAS... on base board; in final assembly completely wired and protection class IP 20; wiring in terminal boxes with protection class IP 65 is possible,
3) as BWK... in metal case; in final assembly completely wired in a terminal box and protection class IP 65, or
4) completely customer and/or application specific
<<

What is a PTC brake resistor?
A PTC component is a ceramic element with positive temperature coefficient, i.e. its resistance value increases as the temperature rises. This dynamic behaviour prevents excessive energy input and provides the element with self-protection. The PTC resistor we supply, which was further developed by us into a true brake resistor for use at the DC link of the power converter, distinguishes itself particularly by its voltage strength of up to 1,100 Volts direct current (dependent on the resistance value).
<<

What does KOCH mean by intrinsic safety?
This definitely does not mean intrinsic safety in the sense of explosion protection!
The term is used in a business-specific definition referring to the base electrode of the resistors.
a) Intrinsic safety for wire-wound resistors means:
In the event of constant overload (for instance, brake transistor (brake chopper) short-circuit) there is
- no short-circuit
- no internal isolation breakdown
- no fire
- no explosion
- no melting of the aluminium case
b) PTC brake resistors are safe due to their dynamic behaviour: the higher the temperature, the higher the resistance value. Once a certain temperature is reached, the resistance value is so high, that no more energy input occurs - the PTC resistor protects itself.
<<

How does KOCH design?
The optimum resistor is proposed based on the exact survey and analysis of the drive chain. The general set-up of the cycle time and brake time (power-on time), the maximum and normal brake power with respect to continuous power play decisive roles in the selection. The resistance value is either predefined by the converter manufacturer or will be calculated taking account of the general set-up. Our calculation program, available here online, is useful for initial considerations. It is also worth taking a look at the power / power-on time diagram, which shows the power (in Watts) against the relative power-on time (as % of the cycle time (as a rule, 120s)). We have chosen the double logarithmic view, in order to make clear the linear load limits at ambient temperatures of 70°C and 20°C. You will recognise the ability of the resistors to absorb high inputs for a short time.
<<

How does KOCH define the various terms and expressions used for electrical power?
The impulse power PI is defined as the short-time power absorbed by the resistor without reduction of the service life at an ambient temperature of 70°C and a maximum surface temperature of 250°C. The KOCH resistors achieve their specified PI with free convection, that is without additional cooling of any kind. The limiting factor is the energy absorption capacity of the resistance wire. By virtue of the construction of the KOCH resistors, the heat is slowly systematically diffused to the surface. Short impulses therefore often cause a slight increase in the surface temperature. The continuous power PD, like the nominal power PN is defined as the continuous power absorbed by the resistor without reduction of the service life at an ambient temperature of 70°C and a maximum surface temperature of 250°C. The KOCH resistors achieve their specified PD with free convection, that is without additional cooling of any kind.
<<

Why should you decide on KOCH resistors?
We offer many advantages, which will benefit you and your customers:
- Good price/performance ratio
- Resistors developed exclusively in accordance with electrical drive engineering requirements
- Product safety
- high protection class IP 65 (for wire-wound resistors)
- cCSAus-cURus-approval
- short delivery times
- absolutely dependable delivery reliability
- Individualisation (OEM labelling and packaging) possible
- friendly and attentive service
- active support
- target-oriented support: personally, with paper documents, or via the Internet
- complete flexibility (exception: reduction of product safety)
- electrical and mechanical engineering
- customer and/or application specific resistors and peripheral equipment from one source
- Innovative partner with QM and environment certifications
- Oriented to long-term and sustainable growth targets
<<

Which resistance value tolerances does KOCH offer?
Our wire-wound resistors have a tolerance in the resistance values of + 5%. Smaller tolerances are possible for larger quantities at extra cost. PTC resistors as a condition of manufacture have a tolerance range in the resistance value of + 35%. However, based on experience, and depending on the batch the actual tolerance is only < + 10%.
<<

How does the purchase process at KOCH work?
A definitive technical and commercial quotation in accordance with the technical design is made. Every quotation is made in writing by our internal order processing system. Our quotation is binding for four weeks. After you place an order, you will always receive a detailed written order confirmation, usually by fax. Every delivery is accompanied by a delivery note (you specify the number of copies). This is useful for potential defects claims. We supply EX WORKS. The twelve month guarantee period starts now. The invoice is raised on the day of delivery and sent together with the product. As a new customer we expect payment in advance, otherwise within 14 days 2%, 30 days net, plus costs of the credit transfer for foreign orders. We reserve the right to make changes. Terms for foreign orders on request.
<<

Does KOCH also supply temperature monitoring for the resistors?
For wire-wound resistors, we supply an external temperature switch as the solution. For PTC resistors, a temperature monitor, given the type of construction, is fundamentally not necessary. But even for our wire-wound resistors, we do not think a temperature monitor is necessary in most cases on the basis of the costs / usage situation (wiring costs etc.).
<<

Which assembly fittings does KOCH supply?
We supply purpose-built for our selection of wire-wound resistors matched metal brackets (aluminium or high-grade steel (on request)) for the long or narrow sides of the resistor, converter or machine specific substructure frames right up to cases according to your requirements. We make sure, that you can install our resistors optimally in your machine!
<<

What distinguishes a good brake resistor?
It must be able to absorb short but high-power impulses without complaint and without its surface attaining high temperatures. On destruction it must not cause any consequential damage and must have a continuous high Ohm value. It has a low induction, in order to be applicable for the high reaction speeds of modern servodrive technology. It has cCSAus and cURus approval, so that the export of a machine or plant, in particular to North America, is not inhibited.
<<
Please leave a messageWe received your Message. Thanks!Close

Please fill out the form below.

Name*
Company*
Email*
Phone
Add a message