littelfuse FAQ

Frequently Asked Questions For Littelfuse SymCom Protection Relays & Controls

Littelfuse 3/20/2018
Frequently Asked Questions For Littelfuse SymCom Protection Relays & ControlsI have a 777 or 77C product and every time the motor is shut off, the MotorSaver trips and flashes a number alternating with run?
This is a normal condition. Every time the motor is shut off or the MotorSaver is power cycled, the device goes through a rapid-cycle timer (programmed in RD1). This is to prevent the motor from being turned off and on repeatedly in a short period of time. If you are using an alarm on the NC output contacts and do not wish the alarm to go off every time the motor is turned off, set RD1 to 0. Keep in mind, though, this will disable rapid-cycle protection.

I have an LSR (load sensor) and I can't get the relay contacts to energize?
The LSR will only energize its contacts if it sees current greater than the setpoint value. This setpoint value can be 2-100A and is regulated using a 20-turn pot. For example, if you are only looking at 10A, the setpoint screw needs to be turned several times counterclockwise until the setpoint is <10A, then the contacts will energize.

I have a 777 (or 77C or 601) and when I try to change a setting, the number jumps back to the previously programmed value?
You have the Tamper Guard on. To unlock the Tamper Guard, turn the MODE SELECT dial to GF (OPT2 for a 77C, 4LFT for a 601). Push in and hold the RESET/PROGRAM button and turn the DISPLAY/PROGRAM dial clockwise until you see "unL" on the display. Release the button. After changing the settings, you can lock the Tamper Guard by following the same instructions except turn the dial until you see "Loc." This will prevent anyone from accidentally changing the settings.

My 777 tripped on "ub." Is that current unbalance or voltage unbalance?
Current unbalance. Our devices will give a voltage unbalance reading at the initial power-up and will prevent the motor from starting. Once the motor is running, a "ub" trip is due to a current unbalance.

My 777 displays current readings jumping around from 0 to 6A, but my clamp-on ammeter reads 3A (as an example, numbers may vary)?
The 777s will only read current above about 7A. You probably need to loop your conductors through the holes a greater number of times (i.e. down through each round hole, back up through each rectangular hole, back down through each round hole, etc.). Refer to the installation guide to review the setup procedure. Don't forget to reprogram the MULT setting if you change the number of conductors through the unit.

I heard there's a high sensitivity mode for PumpSavers. How do I utilize this feature?
PumpSavers trip on an underload (dry-well) condition when the current drops below 80% of the calibrated value. Sensitivity may be increased to 87% of the calibrated value.

Do I need to turn the knob back to RESET on the PumpSaver to calibrate it?
No. To calibrate, simply turn the dial fully counter-clockwise to CAL while the pump is running under normal conditions. The CAL light will be on for about 10 seconds. Once the pump turns off turn the dial out of the CAL position (the pump will turn back on) and adjust to the desired restart delay setting. You're all set! The RESET position has two functions:
It can be used if the PumpSaver has tripped and is timing through its restart delay. Turn the dial to RESET, and then back to the desired restart delay setting to restart the pump. It can also be used as a manual restart setting when automatic restarting is not desired.

Do I need to recalibrate the PumpSaver after a power loss?
No. The PumpSaver will remember the last calibrated values permanently.

My 777 tripped and reads "CF" on the display?
This is a contactor failure fault. This occurs when the device sees a large current unbalance (>50%), but no voltage unbalance. Turn the MODE SELECT dial to VUB (voltage unbalance) to check the setting. If it is high (>6%) set it to a lower number such as 6%. If there is a substantial current unbalance along with a voltage unbalance, the unit will trip on single-phasing ("SP"), but will restart when conditions improve and it times through restart delay programmed into RD2.

When do I need an HVR model version?
HVR products have a High Voltage Relay rated 480VA @ 600VAC pilot duty. These products can be used to switch 480V controls (or 575V controls on a Model 350-600) when No Control Power Transformer is Used.

Can I use a 777-HVR with 240V controls?
Yes, but you must have 380-480VAC input voltage. It's not necessary to have the higher voltage relay, but it will function the same.