FAQs

ACE offers repair services and accepts returns via its Repair Information page. Customers should initiate a return or repair request via the designated portal. (See our Repair Information page for full details.)

Our standard warranty covers defects in workmanship and materials for 12 months or 3,000 hours, whichever occurs first. This warranty applies to standard catalog products only (not specials) and includes free repair or replacement at our discretion.

We accept cash, checks, money orders, Visa, MasterCard, American Express, and Discover. For established customers, payment terms are Net 30 days from shipment. For export orders or new customers, special terms may apply.

Products are shipped F.O.B. (Freight On Board) from our location. Freight, handling fees, and applicable taxes are charged to the customer. Title and risk pass to the customer once shipment is tendered to the carrier.

Yes. We offer drives certified as UL Listed (the fully tested unit) as well as drives with UL Recognized (components certified, but unit not fully tested). We also support cUL / cUR for Canada.

For electronic controls, a CE marking indicates compliance with European electrical safety and electromagnetic compatibility (EMC) standards. In practice, this means the drives are lab-tested to ensure they safely manage power distribution and meet strict limits on electrical noise emissions and immunity.

SCR stands for Silicon Controlled Rectifier. It’s a semiconductor device used in many DC motor drives to control voltage by switching on and off rapidly.

PWM (Pulse Width Modulation) is a method of applying a fixed amplitude DC voltage in pulses at high frequency. By adjusting the width (duty cycle) of the pulses, the average voltage (and thus motor speed and torque) is controlled.

A Variable Frequency Drive (VFD) controls the speed and torque of an AC motor by generating a 3-phase power output with a variable amplitude and frequency. While primarily used to control 3-phase induction motors, certain VFD configurations can also be applied to specific single-phase motors.

A 4Q (regenerative) drive can handle motoring and braking in both directions (forward and reverse), feeding energy back into the supply during braking. A 1Q drive handles only unidirectional motoring (i.e. forward direction, deceleration via coasting or external braking).

Yes, many ACE drives support dual input (115/230 VAC) and can output 90 VDC or 180 VDC depending on the configuration switches. However, keep in mind that running a 90 VDC motor from a 230 VAC input via SCR control degrades the DC form factor, which increases motor heating and requires the motor to be derated.

Signal isolation means providing galvanic isolation between the low-voltage control circuitry and the high-voltage power circuits. This allows the drive to safely receive speed command signals from external devices, whether they are floating or referenced to earth ground.

In voltage follower mode, the drive output voltage follows (proportional to) an external control voltage from a device such as a PLC or computer.

In DC drives, the armature output supplies the motor’s main winding with a variable DC voltage to control speed and induce rotation. The field output provides a fixed DC voltage to a shunt or wound-field motor’s field winding, creating the steady magnetic field required for the armature to react against.

With SCR drives, you generally do not need to have a motor connected to measure the DC output voltage. However, with drives that use PWM technology, such as VFDs and BLDC drives, a motor must be connected because the drive requires the motor's electrical characteristics to operate the output transistors.

Use acceleration/deceleration ramp settings (ACCEL/DECEL trim pots or programming) rather than abrupt changes. If stops are very frequent or require holding the motor, consider using the inhibit/enable input or a drive with braking/regeneration capabilities.

The inhibit (sometimes called enable) function disables or enables the drive output via an external logic input. It’s commonly used for safety, control interlocks, or integration with PLCs.

No. A drive’s logic should never be relied upon for emergency stopping as it is best to assume the logic can fail in this circumstance. The removal of power is the only recommended e-stop.

A thermal overload switch monitors motor temperature or current. In the event of overheating, it opens the circuit to prevent damage. It should be wired to the appropriate input of the motor controller to command a stop.

A tach generator produces a voltage proportional to motor speed. That feedback is fed back into the drive to tighten speed regulation and improve responsiveness under load changes.

A Hall sensor detects the presence or strength of a magnetic field (often used in brushless motors). It’s often used for rotor position sensing to provide commutation feedback.

A magnetic pickup (or magnetic sensor) senses passing ferrous gear teeth or slugs and generates a pulse. It’s often used for measuring rotational speed (e.g. on shafts or flywheels).

An encoder outputs a series of electrical pulses (or digital signals) proportional to motion (position, speed, or direction).

A line filter reduces electrical noise and interference on the AC supply side of the drive. It improves EMC (electromagnetic compatibility) and prevents drive or system disturbances.

DC injection braking applies a DC voltage to a phase of a 3-phase motor to generate braking torque without needing mechanical brakes.

A UV TRIP senses when supply voltage drops below a threshold. When triggered, it disables a drive’s output to protect circuits from undervoltage stress or instability.

No. On many drives, you can simulate a 10 kΩ pot with fixed resistors, or tie input terminals (e.g. S2 to S3) to force the drive to maximum speed. However, never short or wire incorrectly, always consult your specific drive manual or seek technical support.

Reversal is usually done by swapping the motor lead polarity. The proper procedure is:

• Turn output voltage to zero or activate inhibit
• Wait until motor stops
• Swap armature leads
• Re-enable output

Some drives support remote or relay-based reversal, follow your drive’s wiring guidelines.

Yes, for example, our MHS and MGC series models include a three-wire Start/Stop feature.

1. Verify line voltage at the drive’s L1 and L2 terminals.
2. Confirm motor wiring and connections are intact.
3. Ensure the control / command signal (pot, analog input) is present and varying.
4. Check inhibit/enable logic inputs.
5. Verify trim pot settings (Max Speed, Current Limit, etc.).
6. On some models, ensure input voltage selector switches are set correctly (e.g. 115V vs 230V).

Possible causes:

• Motor is grounded (check insulation to chassis)
• Dirty power or voltage spikes (consider AC line filter)
• Miswiring (e.g. armature output tied to field output incorrectly)
• Exceeding drive/motor current or ambient temperature rating
• Non-isolated signal wiring causing ground loops or shorts

This may be due to incorrect trim pot settings (Max SPD pot fully CW), a disconnected or shorted speed command input or damaged control.

Oscillation can result from over-compensation in IR control, poor tuning of trim pots (ACCEL/DECEL, IR COMP), or unstable feedback loops (if using tach or encoder). Try reducing IR compensation or adjusting ramps.

This can stem from misconfigured feedback scaling, incorrect speed command signal (i.e. 0–10 V command mapping), or MAX Speed trim pots being misadjusted.

The drive may be current limiting. The current limit trim pot may be set too low, or the motor is undersized. Increase current limit or select a drive or motor with higher current capacity.

If using an SCR style control, this is normal. The bussing is caused by the switching of DC voltage to the motor at a relatively low frequency. If this is an issue, consider a PWM type drive.

MIN SPD (minimum speed) sets the lowest speed the drive will output when the main speed command signal goes to zero. In most cases, this is set to zero.

MAX SPD (maximum speed) defines the maximum speed the motor will achieve when the external speed command signal is the highest.

• ACCEL: sets how quickly the drive ramps from zero to commanded speed (i.e. acceleration time)
• DECEL: sets how quickly the drive ramps down its output voltage to the motor (i.e. deceleration).

In single-pot configurations, one pot may serve both functions with tradeoffs.

Advantage: easier tuning (just one trim pot). Disadvantage: you lose independent control, which may be suboptimal for applications needing different ramp rates for acceleration vs deceleration.

IR Compensation boosts voltage in proportion to motor current under load, helping maintain consistent speed under varied loads. Turning the IR COMP pot CW increases compensation but too much can cause oscillation.

The CURRENT LIMIT pot sets a ceiling on motor current. If the motor draws more than that, the drive reduces voltage to prevent damage. Turn the pot CW to raise the limit.

This is essentially the same as CURRENT LIMIT (limiting torque via current). Refer to the current limit setting for guidance.

BOOST is used mostly on VFD motor controls. It injects extra voltage at low speeds to help start high inertial loads. Use carefully, as too much boost can cause excess motor heat.

SLIP COMP (slip compensation) is similar to IR COMP but used in VFD drives. It compensates for the speed difference (“slip”) between the motor’s rotor and stator under load, boosting voltage to resist speed drop.