Frequently Asked Questions we would like to answer
ABOUT ELECTRONIC MOTOR PROTECTION RELAYS
Q. Why would you recommend I use your electronic motor protection relays? I have been using the thermal bimetals for many years and have not experienced any problems. The latter are also much less expensive.
Q. If all of your relays provide the BASIC protection requirements that you have outlined above, what is the purpose of having the diverse range shown in your catalogue?
ABOUT THE COMPANY
Q. What experience does NewElec have in the field of motor protection?
Q. Do you cater for the needs of the automation and process control industry?
Q. Do you design and manufacture electronic motor protection relays yourselves or do you import such products?
Q. Do you service your range of products?
Q. Could you mention some companies or corporations for whom you are supplying motor protection relays?
Q. Do you comply with any manufacturing process standard?
Q. Are your products SABS approved?
Q. Does your company export any of its products?
Q. Do you provide training for your product range?
ABOUT PROTECTION TERMS AND BASIC SETTINGS - COMMON QUESTIONS
Q. Please explain how I set my motor full load setting on a % calibrated load setting dial?
Q. Where exactly do I place the external phase current sensing transformers or, in the case of relays incorporating built-in current transformers, the actual relays?
Q. What is a thermal curve class?
Q. Will a motor draw the same amount of current while starting Direct On Line as it would in a stall condition?
Q. What is thermal memory?
Q. Will the thermal memory be retained if the power supply to the relay is removed?
Q. What are pre-loaded curves? Alternatively what is the meaning of pre-loading the protection relay?
Q. What is meant by “fail safe”?
ABOUT PROBLEMS EXPERIENCED ON SITE
Q. Shortly after starting or during the start sequence of the motor your protection relay trips the motor on unbalance. What could cause this?
Q. I am using one of your relays having a fixed 15-second cold thermal curve on a conveyor belt motor requiring 27 seconds to reach full operating speed. It is a D.O.L application involving a 110 kW motor at 380 Volt a.c. Your relay keeps tripping on overload during the starting sequence. What could be the problem?
Q. Our geographic location is highly prone to lightning strikes. Are your NewElec relays protected against such high voltage surges on the net- work?
QUESTIONS ASSOCIATED WITH THE NEWELEC 320 – 327 SERIES
Q. My staff complain that your 327 relay trips with all its fault diagnosis “on” or busy flashing. This happens every time we try to start this motor. What can be the problem?
ALTERNATIVELY
Q. My staff complains that your 327 relays keeps tripping on earth fault every time they start the motor. We have meggered the motor and cables but can find no fault. What can be the problem?
Q. The start timer setting on your 327 M relay only permits us a maximum setting of 21 seconds. Our application requires 32 seconds. Consequently we are unable to start our motor without tripping. How can we overcome this difficulty?
Q. Would it be possible to change the auxiliary supply operating voltage of your 320 to 327 relays without returning the unit(s) to your factory for alteration?
QUESTIONS RELATED TO THE NEWELEC N SERIES
Q. The thermal indication LED bar graph on our installed “N” series relays displays different thermal build up even though they are of the same model and used on identical kW motors. Why is this?
Q. What is the purpose of the dial marked “OVERLOAD CURVE 6 X I fl SECONDS” mean? Is it the time required to accelerate my motor?
Q. What does the LED bar graph do?
Q. Why can I not reset the overload protection relay after an overload trip?
