Horse Power (HP): What is this contact rating?

This week we're covering horse power and the associated ratings on our datasheets!

E2021 Tech Tuesday Blog Banner 2019

When I think of horse power (HP), I soon think of the many times Tim “the Toolman” Taylor attempts to soup up whatever power tool was featured on his “Tool Time” episode. Things quickly got out of hand (sometimes literally) as Tim tried to demonstrate his belt sander knowledge. Going along with the theme of explaining some of the contact ratings seen on RIB datasheets, this time I want to cover HP and the associated ratings on our datasheets.

What is Horse Power?

Horse power is like any other unit of power, which is a way to represent a rate at which work is being done. Power represented in watts (W) is closely related to HP. With great power comes great responsibility – responsibility to choose a correctly rated relay! This chart helps to convey the electrical current that is consumed at each HP rating. What’s not displayed is the instance of current consumed if the electrical motor happens to be locked. That results in a very high consumption of electrical current.

HP Ratings for Relays

The HP ratings listed on the 10A, 20A, and 30A rated relays (seen below, respectively) are proven by the UL testing that is performed on the RIB relay devices. With those listed ratings, it is important to notice the specific voltages that are stated. Could our relays handle a 1 HP motor @ 240Vac? Perhaps it could, but we cannot guarantee how long the relay will last. With the listed specifications, the RIB relay devices are guaranteed to last a long life of switching the motor load on and off.

Contact Ratings - Horse Power

Another important note is that these HP ratings are for conventional AC powered motors. Electronically Commutated Motor (ECM) units do not behave – electrically speaking – like a conventional AC powered motor. UL has not yet made standard specifications for ECM units because of manufacturers have different ways of making a motor into an ECM unit. For a more reliable contact rating for ECM units, look at the “electronic ballast” rating.

There you have it. A brief overview of the HP ratings that we have listed on our RIB relay datasheets. I hope this helps you to make a more informed decision of relay size for your next controls project. Please call in and ask for support or email for a second opinion. We engineers are standing by 8am-5pm EST!

Oh, and did you hear about the man who was hospitalized with six plastic horses inside him? The doctor described his condition as stable.

Sam Klennert
Sam Klennert

Meet Samuel Klennert – you can call him Sam. He was born and raised amongst the farmland of Indiana, which includes corn, soybeans, and sometimes wheat. Sam graduated from Purdue University with a Bachelors degree in Electrical and Computer Engineering Technology in 2015.

Outside of work, Sam enjoys spending time with his wife and dog – whether it’s inside or outside their home. Sam can also be seen serving at his local church and glorifying God with other believers, which is by far his favorite way to spend time.

Articles: 37